E46 m3 engine rebuild.

[Thenakedflyer]

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

[rossw46]

I can't offer you any advice, sorry, but I'm interested to see what those in the know say, as my M3 also has 110K on the clock, and I too am more and more tempted to get it supercharged. I'd rather know up front whether it'll be more than just the supercharger cost, i.e. new head gasket, new pistons etc.

Also, when selling, how much (if any) more valuable would the car be ?

Hope your rebuild goes well anyway.

[Thenakedflyer]

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

[Thenakedflyer]

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

[SPORTSTER]

When were the valve clearances last done?

When you say Vanos was done, what was actually done? solenoid, bolts, seals, cam timing?

Cylinder 2 & 6 are tad low, the HG maybe at the beginning stage?

Edited by SPORTSTER on Wednesday 5th October 08:47

[AW10]

Those leakdown figures seem high. Are they percent or PSI figures?

[SPORTSTER]

AW10 said:

Those leakdown figures seem high. Are they percent or PSI figures?

Looks like percentage to me

Edited by SPORTSTER on Wednesday 5th October 11:31

[HustleRussell]

SPORTSTER said:

Cylinder 2 & 6 are tad low, the HG maybe at the beginning stage?

Less than 2% variance between the average and the minimum? Head gasket blowing on cylinders 2 & 6, apparently with none of the other cylinders affected and no other symptoms? It sounds to me as though you have no idea.

OP by all means rebuild your engine but based on what you've said here there is absolutely no need and the engine is in all likelihood ready to do the same again barring perhaps the VANOS.

[andyman_2006]

HustleRussell said:

SPORTSTER said:

Cylinder 2 & 6 are tad low, the HG maybe at the beginning stage?

Less than 2% variance between the average and the minimum? Head gasket blowing on cylinders 2 & 6, apparently with none of the other cylinders affected and no other symptoms? It sounds to me as though you have no idea.

OP by all means rebuild your engine but based on what you've said here there is absolutely no need and the engine is in all likelihood ready to do the same again barring perhaps the VANOS.

---

Mine had exactly the same fault (@ 84k) And was head gasket. Mine went between cyl 1+2 and 5+6 as the block is a 3.0 bored to 3.2 the cyl's are VERY close together, the head gasket (a steel one at that) goes more often between these groups of cylinders which is what the op refers to. The detonation is cross cylinder and hence the symptoms of pinking in high gears low speed etc. The most common is cyl 5+6 as the engine is set quite far back and these are closest the bulkhead and get hotter (which was worse on mine than cyl 1+2) all will be revealed if the op takes the head off. The leak down test is the only way without but % leak will depend how bad it's got. It will only get worse. This HG issue is often mis diagnosed for vanos. It affects all S54 engines including the halo csl.

It's an expensive job, and depending how bad it is depends on whether its justified to be done.

I wish the op best of luck. For ref mine cost £1350 all in. And it's fine now drives best it ever has.

Andy.

[Thenakedflyer]

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

Edited by Thenakedflyer on Wednesday 5th October 17:53

[Thenakedflyer]

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?

[Craigwww]

Thenakedflyer said:

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

Edited by Thenakedflyer on Wednesday 5th October 17:53

Which place would this be?

[Thenakedflyer]

No other advice from anybody?

[Ian_sUK]

I spun a rod bearing at 128K so maybe worth doing them while your at it.

[Thenakedflyer]

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..

[MOTK]

Spun rod bearings are not that rare on these engines at all nowadays. I would definitely be doing those and ARP rod bolts.

[joema]

If it goes or starts misbehaving than maybe worry about it? Unless you actually boost it, then maybe I would.

I'd leave it. Maybe do boot floor if it hasn't been done?

[bucksmanuk]

http://www.cpcpe.com/
Ask for Phil Crouch - very highly regarded in these parts, and hence very much in demand…

[ftypical]

Thenakedflyer said:

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

Edited by Thenakedflyer on Wednesday 5th October 17:53

Over 50k miles since the valves were last done?

Um...

[Nunga]

ftypical said:

Over 50k miles since the valves were last done?

Um...

Thought the same, hoping a service or two has not been mentioned and the clearances have been done more recently...