Surprisingly the manifold nuts all came off as they should this time and left all eight studs in the head... weird, but it certainly made fitting the gaskets a lot easier.
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Showing posts with label Engine. Show all posts
Showing posts with label Engine. Show all posts
Saturday, 16 February 2013
E21 316: More manifold gaskets for M10...
Stuck the new and much better quality exhaust-manifold gaskets on today from Euro Car Parts. They're thicker than the eBay ones and have steel rings round the inner rim like a head-gasket, should make a better seal. It's got rid of the cracking noise from that dodgy one on cyl. 4 [this post] and the engine sounds sweeter than ever.
Surprisingly the manifold nuts all came off as they should this time and left all eight studs in the head... weird, but it certainly made fitting the gaskets a lot easier.
Surprisingly the manifold nuts all came off as they should this time and left all eight studs in the head... weird, but it certainly made fitting the gaskets a lot easier.
Sunday, 10 February 2013
E21 316: M10 Engine cured! - Culprit: manifold gasket...
After repeatedly timing the ignition perfectly to Z on the flywheel, [see this post], we decided there had to be something deftly wrong to be causing the loud noise and backfiring [in the vid below], rather than just the distributor being out of line.
The first hunch was the exhaust had broken while being twisted to get the cylinder-head out and was blowing like mad, but my initial inspections revealed no damage to the down-pipe or manifold and the four manifold gaskets looked all to be in position.
That is to say they LOOKED in position... Today, in the pouring rain, I got the car up on ramps to see what it was I'd missed and as soon as the torch flicked on I could see the answer at last - one of the exhaust-manifold gaskets had slipped off the stud and was only covering half the hole! Nightmare... Right at the back of the engine where we couldn't see and, ironically, the one for cylinder 4 that started all the trouble.
As you can see the gasket has been totally blown apart by the hot exhaust and has separated quite badly in the middle leaving only the metal. I checked the rest of the gaskets in my set for a spare, but can only find the same shape gasket with an oblong hole, perhaps for the E28, so tentatively decided to re-use the blasted one, correctly seated this time and caked in Holt's FireGum.
As soon as the engine fired up again it sounded like it used to. It's amazing the difference that gap in one single exhaust port made to the noise level. It was still idling low though and revving badly, so I grabbed the timing-light again to have another go, turning the distributor to line up Z on the flywheel - 25 degrees before TDC. Now the 30 year old M10 has really begun to purr once more. Awesome! Still some fettling to do on the carb. tuning, throttle/choke cables and checking to see if my damaged manifold-gasket is holding up, but at least she's back on the road after a tense month!
The first hunch was the exhaust had broken while being twisted to get the cylinder-head out and was blowing like mad, but my initial inspections revealed no damage to the down-pipe or manifold and the four manifold gaskets looked all to be in position.
That is to say they LOOKED in position... Today, in the pouring rain, I got the car up on ramps to see what it was I'd missed and as soon as the torch flicked on I could see the answer at last - one of the exhaust-manifold gaskets had slipped off the stud and was only covering half the hole! Nightmare... Right at the back of the engine where we couldn't see and, ironically, the one for cylinder 4 that started all the trouble.
As you can see the gasket has been totally blown apart by the hot exhaust and has separated quite badly in the middle leaving only the metal. I checked the rest of the gaskets in my set for a spare, but can only find the same shape gasket with an oblong hole, perhaps for the E28, so tentatively decided to re-use the blasted one, correctly seated this time and caked in Holt's FireGum.
As soon as the engine fired up again it sounded like it used to. It's amazing the difference that gap in one single exhaust port made to the noise level. It was still idling low though and revving badly, so I grabbed the timing-light again to have another go, turning the distributor to line up Z on the flywheel - 25 degrees before TDC. Now the 30 year old M10 has really begun to purr once more. Awesome! Still some fettling to do on the carb. tuning, throttle/choke cables and checking to see if my damaged manifold-gasket is holding up, but at least she's back on the road after a tense month!
Sunday, 3 February 2013
E21 316: M10 Distributor/Ignition Timing: Strobe Light Ahoy!
So my adventures into re-timing the spark-plugs continue with the purchase of a Gunson Xenon timing strobe-light! I went for the cheapest kit in Halfords, but it was still a slight pain at £45, considering it's in addition to a new dizzy-cap and rotor-arm, set of spark-plugs, compression-test kit, gasket-set, oil, coolant and a 30mm socket to turn the engine from the crank, but as I just can't seem to get the old M10 engine running happily I guess it's just as vital and at least we can use it to time in our old MGA engine this summer (hopefully).
Before I start to moan again about the intricacies of re-timing the distributor I should say that I know there is no need to remove it in order to get the cylinder-head off and the dizzy should really be left in place to save all this trouble, but the diaphragm on mine was blocking one of the head-bolts so that wasn't an option for me.
The timing light works by flashing every time your 1st-cylinder spark-plug fires. There is a timing-mark on the spinning crank-pulley or flywheel that passes a stationary mark on the block at the exact point the 1st spark-plug should be firing. When the flashing light from plug 1 is aimed at the spinning pulley it shows the timing-mark in a fixed position in relation to the stationary mark and allows you to gauge how how many degrees before or after the correct point the spark is. Clever stuff.
On the BMW M10 engine, there are two timing-marks on the flywheel, one for top dead-centre [TDC] and another, called Z, that corresponds to the right point before TDC that the 1st spark-plug should be firing. The marks are visible with the flashing light through a small oblong hole at the back of the crankcase. It's easy enough to find the hole, but seeing into it with the timing-light is a challenge in itself, let alone trying to adjust it or move the dizzy-cap and I ended up having to stand over it with my feet on the strut-tops to steady myself enough without leaning in from the side and crushing the wheel arches. There is another TDC timing-mark on the rearmost rim of the front crank-pulley, which is a lot easier to see with the timing-strobe from the n/s of the engine-bay, but the mark is tiny so when you do find it it's best to file a larger notch across the whole pulley - mine had this done already and it makes things a lot clearer.
It's best to first time your engine to Z on the flywheel, at 2200rpm, using 0 degrees of advance on the timing-light gun - just shine it into the oblong hole and rotate the distributor-cap until the large pointer is lined up with the silver ball, not the TDC line. Now check the front crank-pulley for reference by shining the light at it with 0 degrees advance. The groove for TDC should appear around 25 degrees before the stud on the engine-block. Rotate the dial on the timing gun slowly to 25 degrees and the groove should move in line with the pin. Simples.
Ignition timing isn't too much of a fine art, so as long as the rotor-arm contact is roughly on point no.1 on the dizzy with the engine at top dead-centre then it should fire right up and not need much adjustment to find Z. Mine was still making the god awful noise after repeatedly timing to Z, but this turned out to be a badly positioned exhaust-manifold gasket [in this post] so, obviously, check everything else isn't amiss before starting to mess with ignition timing.
Before I start to moan again about the intricacies of re-timing the distributor I should say that I know there is no need to remove it in order to get the cylinder-head off and the dizzy should really be left in place to save all this trouble, but the diaphragm on mine was blocking one of the head-bolts so that wasn't an option for me.
The timing light works by flashing every time your 1st-cylinder spark-plug fires. There is a timing-mark on the spinning crank-pulley or flywheel that passes a stationary mark on the block at the exact point the 1st spark-plug should be firing. When the flashing light from plug 1 is aimed at the spinning pulley it shows the timing-mark in a fixed position in relation to the stationary mark and allows you to gauge how how many degrees before or after the correct point the spark is. Clever stuff.
On the BMW M10 engine, there are two timing-marks on the flywheel, one for top dead-centre [TDC] and another, called Z, that corresponds to the right point before TDC that the 1st spark-plug should be firing. The marks are visible with the flashing light through a small oblong hole at the back of the crankcase. It's easy enough to find the hole, but seeing into it with the timing-light is a challenge in itself, let alone trying to adjust it or move the dizzy-cap and I ended up having to stand over it with my feet on the strut-tops to steady myself enough without leaning in from the side and crushing the wheel arches. There is another TDC timing-mark on the rearmost rim of the front crank-pulley, which is a lot easier to see with the timing-strobe from the n/s of the engine-bay, but the mark is tiny so when you do find it it's best to file a larger notch across the whole pulley - mine had this done already and it makes things a lot clearer.
It's best to first time your engine to Z on the flywheel, at 2200rpm, using 0 degrees of advance on the timing-light gun - just shine it into the oblong hole and rotate the distributor-cap until the large pointer is lined up with the silver ball, not the TDC line. Now check the front crank-pulley for reference by shining the light at it with 0 degrees advance. The groove for TDC should appear around 25 degrees before the stud on the engine-block. Rotate the dial on the timing gun slowly to 25 degrees and the groove should move in line with the pin. Simples.
Ignition timing isn't too much of a fine art, so as long as the rotor-arm contact is roughly on point no.1 on the dizzy with the engine at top dead-centre then it should fire right up and not need much adjustment to find Z. Mine was still making the god awful noise after repeatedly timing to Z, but this turned out to be a badly positioned exhaust-manifold gasket [in this post] so, obviously, check everything else isn't amiss before starting to mess with ignition timing.
Monday, 14 January 2013
E21 316: M10 Misfire Woes:
Went on a Maccies run with some work colleagues on New Year's Eve and I may have been pushing the old girl a bit hard, when a horrible clanging noise began from the engine and got worse quickly. Some of the guys at work suggested the first stop should be the rotor-arm and dizzy-cap so we managed to get some delivered through the parts dept. that afternoon, but it was still chugging on a mixture of cylinders and it limped home for me then refused to start again. When it eventually did the old M10 barely managed to fire 3 cylinders.
My list of diagnostic checks was:
Replaced distributor-cap and rotor-arm.
Tested all 4 plug-leads.
Replaced all 4 spark-plugs.
Removed, cleaned and rebuilt Weber carb.
Checked valve-clearances and confirmed all valves appear to be moving correctly, turning the engine by hand.
Finally diagnosed cylinder 4 as no firing.
Plug and lead tested again, this time sparking against the suspension turret.
Compression test revealed Cyl. 1 and 2 @ 150psi, 3 @ 45psi and 4 @ 25psi.
This all seems to point to a bust head-gasket between the 3 and 4 cylinders. It is unlikely the valves for 2 cylinders would have bent or suddenly need adjusting at the same time, so off with its head and lets look at that gasket.
*UPDATE: The head came off pretty quickly and revealed one seriously blown head-gasket right between the 3rd and 4th cylinders [detailed pics in this post]. Diagnosis spot on, but the culprit may be a slight warping at that end of the alloy-head - not very much at all, but still a worry considering it looks to have been skimmed before. Either way, the new head-gasket is on [I went for a full head set off eBay for £27.99, which includes the manifold gaskets etc.] and the car is running on all four cylinders again, though not as happily as it could be. I was forced to remove the distributor and seem to be having some issues with ignition timing since putting it back [in this post], and the carb. still hasn't been tuned properly since the rebuild, so a range of fettling awaits before I can drive it for the first time in 2013.
My list of diagnostic checks was:
Replaced distributor-cap and rotor-arm.
Tested all 4 plug-leads.
Replaced all 4 spark-plugs.
Removed, cleaned and rebuilt Weber carb.
Checked valve-clearances and confirmed all valves appear to be moving correctly, turning the engine by hand.
Finally diagnosed cylinder 4 as no firing.
Plug and lead tested again, this time sparking against the suspension turret.
Compression test revealed Cyl. 1 and 2 @ 150psi, 3 @ 45psi and 4 @ 25psi.
This all seems to point to a bust head-gasket between the 3 and 4 cylinders. It is unlikely the valves for 2 cylinders would have bent or suddenly need adjusting at the same time, so off with its head and lets look at that gasket.
*UPDATE: The head came off pretty quickly and revealed one seriously blown head-gasket right between the 3rd and 4th cylinders [detailed pics in this post]. Diagnosis spot on, but the culprit may be a slight warping at that end of the alloy-head - not very much at all, but still a worry considering it looks to have been skimmed before. Either way, the new head-gasket is on [I went for a full head set off eBay for £27.99, which includes the manifold gaskets etc.] and the car is running on all four cylinders again, though not as happily as it could be. I was forced to remove the distributor and seem to be having some issues with ignition timing since putting it back [in this post], and the carb. still hasn't been tuned properly since the rebuild, so a range of fettling awaits before I can drive it for the first time in 2013.
Sunday, 13 January 2013
E21 316: Head Gasket - well and truly blown!
Here are some pics of the blown head-gasket that turned out to be the misfire culprit [from this post: ] and it turned out my forum-eductaed guess was right and it had failed right between the 3rd and 4th cylinders. Kaboom!
No damage to the water/oil galleries thankfully, but still a catastrophic way for the gasket to fail so quickly under a bit of load. You can see best in the bottom pic of the head where the gasket has begun to fail at the left side of cylinder 4, taking that down and then blowing through to cyl. 3. Not good. An examination of the cylinder-head when removed showed that it is warped a tiny bit, so it looks like the engine has been overheated at some point before I got the car and this is probably going to happen again. Oh well, priest-like driving will be the order of the day unless I just go seat-of-the-pants until it goes again, but in the long-term, an M44 engine-swap from a more modern 318is is looking like a must!
Saturday, 5 January 2013
M10 Engine: Weber Carb. Rebuild [Twin DMTL]
As mentioned in this post [], rebuilding my Weber DMTL carburettor was one of the first things on my list of curing my misfire problems, which turned out to be a more serious blown head-gasket. Still, restoring the carb. is one of the first things the previous owner told me I should do and gave me a brand new Weber rebuild-kit with the car, so I guess it can't hurt the old girl.
This job isn't for the faint hearted though, so if you have a disposition towards botching fiddly things as I generally do, then it's probably best left to a pro - I messed up my throttle-cable and had to replace it, and fettling the throttle-spring arrangement was all but impossible to get back to how it was. It's still not right, throttle springs etc. a bit loose, but at least its running ok again.
Here's a great guide for tuning the carb. once it's rebuilt: http://www.carburetion.com/Weber/adjust.htm
**CAUTION: If you're running a Weber on an E21 then your 'Bowden' throttle-cable will likely have been cut to fit through the cable-eye on the throttle linkage. Cutting the metal end off the cable causes it to lose its tension and the strands begin to unravel immediately so be very careful when removing and fitting the cable to the carb. [especially if you need to do it more than once which broke mine], as once the cable has begun to expand inside the sheath it binds very easily and you will need a new one. These aren't in production anymore either and I got the last one from BMW Classic in Park Lane, though I'm sure plenty are still out there, but still save yourself the worry!
Tuesday, 9 October 2012
E21 316: New Thermostat working well.
The coolant problems from this post [Coolant/Radiator Troubleshooting] have been truly rectified with the installation of this new thermostat.
The temp. gauge hasn't risen above halfway since, despite some hard and motorway driving, which is great, but the car seems to take a bit longer than before to reach normal temp. It could mean the thermostat is slightly the wrong temperature range, but both the one I removed and the new one are confirmed 80 CEL, so I think it's likely the car now has a more average heat up time and I'm just not used to it!
PROCESS:
BMW thermostat units are built into tube-housings so replacing them couldn't be simpler, simple pop the hose clamps off each pipe and it pulls straight out.
1. Use a flathead screwdriver to loosen the jubilee-clip holding the lower hose in place on the thermostat, pull the hose clear and allow the coolant to drain from the engine into a container.
2. Loosen the jubilee clip to the top hose on the thermostat and pull the hose clear.
3. Loosen the jubilee clip to the hose on the nearside of the thermostat coming from the coolant-return and pull the thermostat unit clear of the hose.
4. Reverse the process with you're new thermostat.
5. Re-fill the radiator with 3.5-5 litres of coolant. ** It's probably best to back flush the engine and radiator while the hoses are off and the system is drained.
The temp. gauge hasn't risen above halfway since, despite some hard and motorway driving, which is great, but the car seems to take a bit longer than before to reach normal temp. It could mean the thermostat is slightly the wrong temperature range, but both the one I removed and the new one are confirmed 80 CEL, so I think it's likely the car now has a more average heat up time and I'm just not used to it!
PROCESS:
BMW thermostat units are built into tube-housings so replacing them couldn't be simpler, simple pop the hose clamps off each pipe and it pulls straight out.
1. Use a flathead screwdriver to loosen the jubilee-clip holding the lower hose in place on the thermostat, pull the hose clear and allow the coolant to drain from the engine into a container.
2. Loosen the jubilee clip to the top hose on the thermostat and pull the hose clear.
3. Loosen the jubilee clip to the hose on the nearside of the thermostat coming from the coolant-return and pull the thermostat unit clear of the hose.
4. Reverse the process with you're new thermostat.
5. Re-fill the radiator with 3.5-5 litres of coolant. ** It's probably best to back flush the engine and radiator while the hoses are off and the system is drained.
Sunday, 7 October 2012
E21 316: M10 Coolant/Radiator Troubleshooting
The car has no overheating issues, it's running like a dream, but the temp. gauge does have a habit of wandering between slightly over normal during slow driving or standing at idle. With cool air blowing into the cabin the needle goes slightly higher again, but never goes above about half way between normal and 3/4, even going uphill or driven hard. On a clear motorway run with lots of cool air the needle drops and sits about the same distance below centre, reaching as low as half way between 1/4 and normal. I'm thinking either a clogged radiator or a stuck thermostat and everyone has backed me up, but I thought I'd take a hard look at it this weekend and try to diagnose the problem in clarity before swapping anything.
Went to Halford's this morning and bought a pack of Holt's 2-part RAD-Flush [£6.99] and 2 litres of engine-coolant [£15.98]. Drained the system and found plenty of blue coolant in there and no oil, but quite a bit of rusty sludge. The car holds 7 litres of coolant, but I only got about 5 out of it. I removed the radiator [the hoses are off anyway as there's no drain plug] and gave it a good flush with the hose. A lot of rusty sludge and orange water poured out and the water appeared to contain no coolant at all, but once the water had run clear there was no sign of a blockage. I re-fitted and filled the radiator, it took about 5L of water, and poured in the first stage of RAD-Flush, though I'm not sure how it will flush the system if the thermostat won't release coolant.
The instructions say to run the car at fast-idle for 30 minutes, but without knowing if there's water pumping round the block I decided to abort if the engine went hotter than normal. I stopped running the engine at 13.5 minutes as the needle started to reach 3/4 on the gauge. A quick check of the radiator hoses revealed the same story - in-hose red hot and out-hose now freezing, so I'm guessing there's no coolant in the engine itself at all now. This means I can no longer drive the car as I have been until the problem is fixed, unless I back-fill the engine with water through some other hose, but it will require draining again anyway when the new thermostat arrives.
Thermostat:
All signs now point to the thermostat. Here's a couple of good checklists posted on eHow to help diagnose a broken thermostat, or other possible causes with similar symptoms - http://www.ehow.com/list_6018650_signs-car-thermostat-broken.html / http://www.ehow.co.uk/list_6018650_signs-car-thermostat-broken.html.
I re-drained the radiator and it ran almost as clear and cold as it went in. A little hot water came from the thermostat side of the hose, but it seemed to be more of the blue coolant mixture. I removed the top hose to the thermostat and about a litre of the warm blue coolant mixture gushed out, another litre coming as I removed the hose in the thermostat's side. It would seem that the radiator hasn't been part of the cooling-system since I've owned the car!
I got the thermostat completely out and immediately I could see it's stuck completely closed to the radiator hose, and only partially open to the bypass valve. Water is being pumped through the thermostat and straight back to the engine and this, along with the non-viscous fan, is the only thing cooling the engine. Quite frankly, I'm amazed the overheating problem hasn't been more severe! I guess with it being summer I never noticed the lack of hot air and not using the cold-air blower kept it close to normal. I could live without the cold-air during a British summer, but as winter rolls around I've noticed that the side-windows are impossible to de-mist. Warmth from the engine itself does de-mist the screen, but as the weather grows colder I can't be sure - best to fix this problem sooner rather than later.
Just bought a new budget thermostat from GSF car-parts on eBay. It's not OEM quality, but it is guaranteed and is much, much cheaper @ £12.50 with free postage, although I paid £20.40 for included next-day delivery, which is still good. I really hope this proves to be the only problem with the cooling!
Symptoms:
Needle fluctuates between slightly cold and slightly too hot in mixed driving conditions. With heater controls set to hot and the fans turned off temperature fluctuates least, but any attempt to blow air into the cabin, hot or cold, causes the temperature to vary more and only cold air blows regardless of heater setting.
The radiator is plenty full of coolant, but there doesn't appear to be a lot of circulation. The return pipe from the engine to the radiator is red hot, while the send pipe from the radiator to the engine is cool. This pipe should be cooler than the other, but not this cool, so it looks like the radiator valve is not releasing cooled water once the engine has warmed up. Hot water also flows through the heater-core to warm the air, which would explain why I'm not getting any.
Diagnosis:
It's definitely looking like a thermostat stuck in the closed position and not releasing water from the radiator, but the pipe to the thermostat, even where it exits the radiator is also cool to the touch. My temp. gauge also doesn't just go up and up, it fluctuates to cool as well, so it could still just be a case of a clogged radiator. Let's hope it's the latter, because the first thing I'll be doing is a full radiator-flush to see if there's an improvement, then changing the thermostat if the problem persists. If this fails, then it could be a new, and expensive, radiator or one of the harder to source temp. sensors or even the water-pump. Hmm.
Flushing:
Thermostat:
All signs now point to the thermostat. Here's a couple of good checklists posted on eHow to help diagnose a broken thermostat, or other possible causes with similar symptoms - http://www.ehow.com/list_6018650_signs-car-thermostat-broken.html / http://www.ehow.co.uk/list_6018650_signs-car-thermostat-broken.html.
I re-drained the radiator and it ran almost as clear and cold as it went in. A little hot water came from the thermostat side of the hose, but it seemed to be more of the blue coolant mixture. I removed the top hose to the thermostat and about a litre of the warm blue coolant mixture gushed out, another litre coming as I removed the hose in the thermostat's side. It would seem that the radiator hasn't been part of the cooling-system since I've owned the car!
I got the thermostat completely out and immediately I could see it's stuck completely closed to the radiator hose, and only partially open to the bypass valve. Water is being pumped through the thermostat and straight back to the engine and this, along with the non-viscous fan, is the only thing cooling the engine. Quite frankly, I'm amazed the overheating problem hasn't been more severe! I guess with it being summer I never noticed the lack of hot air and not using the cold-air blower kept it close to normal. I could live without the cold-air during a British summer, but as winter rolls around I've noticed that the side-windows are impossible to de-mist. Warmth from the engine itself does de-mist the screen, but as the weather grows colder I can't be sure - best to fix this problem sooner rather than later.
Just bought a new budget thermostat from GSF car-parts on eBay. It's not OEM quality, but it is guaranteed and is much, much cheaper @ £12.50 with free postage, although I paid £20.40 for included next-day delivery, which is still good. I really hope this proves to be the only problem with the cooling!
Wednesday, 5 September 2012
E21 316: Engine-Bay Painting 1.
The engine looks a bit more cared for now!
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