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BMW M54 Cylinder Head Skimming - Dilema

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8K views 13 replies 7 participants last post by  Tiffster 
#1 · (Edited)
BMW issue

HI All,

First time poster Hope your all doing well.

Bit of a long story here, but im looking for advice and will try and keep it quick.

Basically purchased a BMW 530i E39 (2004/53 plate) Champagne Edition 2, with a headgasket which had gone - Previous owner had put fuel into the coolant, after a mix up with a watering can at a filling station.

My brother being a current BMW mechanic, and me having alwised fancied a Champagne Edition decided we could fix it - as labour would be free.

After dis-assimbling it it was clear we needed to get the Head Skimmed, which we did, then we had a exhaust cam snap (Quarry Motors Sourced us a new one)

We tightned it down, and the stretch bolts on the exhaust side where loose on torquing - so im in the process of having all bolts heli-coiled.

My first problem is with how good the repair on the block will be - confident with the guy thats doing it, however he cant guarantee the coil will hold in the block - has anyone had any experience with coils in the block. (hes doing all studs to be on the safe side)

My other worry is the head, the guy who skimmed the head has given me 2 differnt answers too how much was taken off the head. Firstly 15FAL (which is allot i belive) then on confirmation hes said a couple of FAL.

I understand the BMW oversized gaskstets are 3FAL above a normal gasket?

SHould i risk putting the head back on, with an oversized gasket, or am i running the risk of the Valves hitting the top of the pistons? The grooves in the top of the pistons seem to suggest the tollerances are pretty tight?

Quarry are looking for a new head for me, however will i just be in the same boat if i dont know how much has been taken off?

Thanks all

Cheers
Rob

If all else fails
 
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#3 · (Edited by Moderator)
HI All,

First time poster :) Hope your all doing well.

Bit of a long story here, but im looking for advice and will try and keep it quick.

Basically purchased a BMW 530i E39 (2004/53 plate) Champagne Edition 2, with a headgasket which had gone - Previous owner had put fuel into the coolant, after a mix up with a watering can at a filling station. :sarcastic

My brother being a current BMW mechanic, and me having alwised fancied a Champagne Edition decided we could fix it - as labour would be free.

After dis-assimbling it it was clear we needed to get the Head Skimmed, which we did, then we had a exhaust cam snap (Quarry Motors Sourced us a new one)

We tightned it down, and the stretch bolts on the exhaust side where loose on torquing - so im in the process of having all bolts heli-coiled.

My first problem is with how good the repair on the block will be - confident with the guy thats doing it, however he cant guarantee the coil will hold in the block - has anyone had any experience with coils in the block. (hes doing all studs to be on the safe side)

My other worry is the head, the guy who skimmed the head has given me 2 differnt answers too how much was taken off the head. Firstly 15FAL (which is allot i belive) then on confirmation hes said a couple of FAL.

I understand the BMW oversized gaskstets are 3FAL above a normal gasket?

SHould i risk putting the head back on, with an oversized gasket, or am i running the risk of the Valves hitting the top of the pistons? The grooves in the top of the pistons seem to suggest the tollerances are pretty tight?

Quarry are looking for a new head for me, however will i just be in the same boat if i dont know how much has been taken off?

Thanks all :)

Cheers
Rob
If all else fails you could do an assembly with the old gsk and some putty on the crowns , rotate it by hand and check clearances , a pita but safe then you can workout how much the thick gsk offers ?
 
#5 ·
Helicoils don't work - well, not for long. Even if you get the bolts to tighten down okay (most don't) it won't be long before the head lifts again, bringing the helicoils with them. The trouble is that you aren't dealing with ordinary old fashioned head bolts that were torqued to 60lb.ft. You have stretch bolts which are about three times that much loading and they just tear out. Timeserts are supposed to be better but I've seen those fail as well.

I wouldn't waste any more time or £££ on it. Just source a good used engine.
 
#8 ·
We aren't talking about planes, we're discussing a BMW engine. Have you ever fitted helicoils to one yourself?
It's got nothing to do with how strong the helicoil is. It's to do with how soft the block alloy is - and the alloy used in steel liner M52, M52TU and M54 blocks is pretty soft. Many of us have been down this helicoil route with these before and it rarely works for long.
 
#12 · (Edited by Moderator)
This was my worry too, that the Bolts are just going to pull the coils straight from the allready brittle block.

The coils have just been finished (30 mins ago) - the guy was 90% sure they would be fine, and has done plenty others on this 6 cylinder BMW's.

Really dont have loads of $$ to be throwing at a new engine, at the same time i dont want to gp throwing more money when its always going to be terminal - Driving down the motorway as everything goes up in smoke.

I have read somewhere else that the threads on the bolts are a known weak spot.

Just spoken to the Guy who organised the Skim and is sure its 0.15 tho, rather than 15 thou, however thats still not a confirmation to me of how much has come off, and weater or not its greater, and i will have a problem with Valves/Piston contact

Thanks for everyones input :)
It may well work for you. It's not as if these never work but the loading/pull on these stretch bolts once angle tightened twice is pretty heavy.
Considering a good used engine is going to be £7-800 and a lot of hassle to fit, it's worth a go I guess. I'd not do the second angle tighten though - that would be pushing your luck!
 
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