E46 m3 engine rebuild.
Discussion
Hello folks.
Ive been thinking about biting the bullet and putting the car off the road for the winter and doing some overhaul work to the car, few bits of cosmetic work and an engine rebuild or overhaul.. Just not sure how far to go with it. The car pinks a bit now and I'm guessing head gasket.. There was a fault code for vanos but it's since not come back after clearing codes. The engine doesn't smoke use oil or make any odd or strange noises. Vanos was done at 55k miles car now has 110k. I've started a leak down test to gauge the internal health and the first result was 35% which is worrysomely high.. I had to dash off so didn't get to complete the test.. I understand the engine needs to be up to operating temp but to do that is reassembling a fair bit and of course engine cools quite a bit by the time you get the valve cover back off and coils plugs out so I'm wary of how accurate the results may be.. Has anybody with experience of engine building got any advice about head skimming block decking new piston rings and gasket thickness that I shoukd do. I'm very capable mechanically and confident of being able to do a rebuild in my own time. Any advice where and what to buy oem or better quality aftermarket parts is much appreciated. If like to build an engine that could perhaps take a bit of tuning perhaps even supercharged. Any advice on this from those that know is much appreciated. Many thanks
Jim
Ive been thinking about biting the bullet and putting the car off the road for the winter and doing some overhaul work to the car, few bits of cosmetic work and an engine rebuild or overhaul.. Just not sure how far to go with it. The car pinks a bit now and I'm guessing head gasket.. There was a fault code for vanos but it's since not come back after clearing codes. The engine doesn't smoke use oil or make any odd or strange noises. Vanos was done at 55k miles car now has 110k. I've started a leak down test to gauge the internal health and the first result was 35% which is worrysomely high.. I had to dash off so didn't get to complete the test.. I understand the engine needs to be up to operating temp but to do that is reassembling a fair bit and of course engine cools quite a bit by the time you get the valve cover back off and coils plugs out so I'm wary of how accurate the results may be.. Has anybody with experience of engine building got any advice about head skimming block decking new piston rings and gasket thickness that I shoukd do. I'm very capable mechanically and confident of being able to do a rebuild in my own time. Any advice where and what to buy oem or better quality aftermarket parts is much appreciated. If like to build an engine that could perhaps take a bit of tuning perhaps even supercharged. Any advice on this from those that know is much appreciated. Many thanks
Jim
Yeah.. I'm interested in either nitrous or supercharger just something different but the most important thing for me is to do a good solid reliable rebuild with possibly if advised uprated components for future power gains if I decide to do that later.. If the head and block need skinned then you need a thicker gasket so not sure if that's compatible with increased power. I'm sure I'd read bmw recommend not skimming block or head :-o
Just an update..
Did a compression test today after running the engine up to temp. Readings were 175, 172, 177, 180, 175, 172. Seem ok if factory is 175.
I also did a leak down test cold and after running the engine up to temp.
Warm readings were 11.5, 15, 13.5, 11, 16, 14
Cold readings 16, 17, 18, 18, 18, 18 if any use.
Are these results ok? Within tolerance for 110k serviced engine? There was noticeably more hissing from plug hole 1 when number 2 was under teak test and same from plug hole 2 when cylinder 1 was under test. So is it a logical conclusion that I might have a blown.gasket between 1 and 2? Or do the results not necessarily back this up as the leak test results weren't markedly worse there? Any advice on the way forward is much appreciated...
Anybody comment?!
Cheers
Did a compression test today after running the engine up to temp. Readings were 175, 172, 177, 180, 175, 172. Seem ok if factory is 175.
I also did a leak down test cold and after running the engine up to temp.
Warm readings were 11.5, 15, 13.5, 11, 16, 14
Cold readings 16, 17, 18, 18, 18, 18 if any use.
Are these results ok? Within tolerance for 110k serviced engine? There was noticeably more hissing from plug hole 1 when number 2 was under teak test and same from plug hole 2 when cylinder 1 was under test. So is it a logical conclusion that I might have a blown.gasket between 1 and 2? Or do the results not necessarily back this up as the leak test results weren't markedly worse there? Any advice on the way forward is much appreciated...
Anybody comment?!
Cheers
Thanks for responses folks. Yes the leak down figures are percentages and I did the test a number of times on each cylinder until consistent readings on the gauges and took an average of them for each cylinder. tbh I have no idea when the clearances were last done but the last insp two was at 49k. I have thought whether the hissing between 1 and 2 could be valves not seating fully but maybe somebody else more knowledgeable about the valve timing will be able to advise??.. All the stuff you read about general.engine health point that these results are fine and I should just enjoy the car, however I understand that these engines with their high specific output generate their power as a direct result of cylinder head pressures which need to be good if you're going to get power. I've been looking at costs to do the head gasket and can get a head pressure test skim if required Inc clean up lap valves and do clearances for 600. New head gasket kit and bolts is about 210 I believe from bmw. The only proviso is that the block is OK and there arent any cracks or bent valves.. Can't see why there should be tbh.. A place in Glasgow who put out 30 rebuilt BMW engines a week do a fully guaranteed m3 engine new vanos gaskets water pump etc for 2800 plus vat.. Kinda tempting I have to say...
Any advice..
Cheers guys
Any advice..
Cheers guys
Edited by Thenakedflyer on Wednesday 5th October 17:53
Also having read plenty online about camshaft timing and removing vanos etc I'm slightly puzzled about my valve timing.. The holes through the camshaft that are used to fix them in.place and stop rotation are I believe supposed to be at 90 degrees to the surface of the head.. The inlet cam is but the exhaust cam is about 30 degrees off.. Is this normal?
Jeeso.. Very rare by all accounts.. Gotta stop somewhere! May aswell get an exchange new engine if I was going to go to that bother...
Plan is head pressure tested skimmed if required de coaked valve seals valves lapped in. Camshafts bolted in valve clearances done. Then back on with new hg and stretch bolts. Vanos is already a replacement unit and was working fine. Then I'm going to replace the Smg pump motor as it makes a fair noise and will no doubt be in a poor state..
Currently trying to get the intake plenum off.. Not easy..
Plan is head pressure tested skimmed if required de coaked valve seals valves lapped in. Camshafts bolted in valve clearances done. Then back on with new hg and stretch bolts. Vanos is already a replacement unit and was working fine. Then I'm going to replace the Smg pump motor as it makes a fair noise and will no doubt be in a poor state..
Currently trying to get the intake plenum off.. Not easy..
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