Head gasket going

Post Tue Apr 12, 2005 5:19 pm

I've come to the conclusion that my head gasket is leaking. Symptom are:

1. Coolant level going down all the time = leaking somewhere

2. Misfiring on one or two cylinders when running from cold = water leaking into cylinder(s) and wetting plug(s) hence no spark

3. Clouds appearing behind me for the first few minutes = burning off the water

4. Petrol consuption dying = not sure how this is connected, but i'm guessing it is.

Anyway, BMW want the best part of Ãƒ”šÃ‚£500 to change the gasket, but of course i aint going down that road. Waiting for a quote from my local garage, but it's still going to be pricey.

The other option is to do it myself, which i should be able to achieve, having done them on previous cars and i've also had the inlet manifold of this one not that long ago. Exhaust manifold has also recently been off, so those studs shouldn't be that difficult to remove.

Question is - are there any other pitfalls or problems i should know about?

Secondly, what else is worth doing whilst the head is off? I was advised to get the head skimmed - is this a good idea?

I think i'll read up on Adam's article on reconditioning the head to see what's involved there.

Post Tue Apr 12, 2005 5:26 pm

i think you have to skim the head..

Post Tue Apr 12, 2005 5:37 pm

What engine is it ?

Post Tue Apr 12, 2005 5:50 pm

Have you got oil in the water or vice versa?

If not, I would want to be certain it was the head before taking it apart.

The misfiring could be down to something else.

The smoking for the first few minutes - they all do that. It would burn any water in the cylinders after the first few seconds of running if it were a leak.

Coolant leak - this is only real symtom. I would have a good look round the engine for leaks, while running and when sat. Look for leaks under the car also after it's been sitting (i.e. overnight)

The bad fuel comsumption and the misfire could be linked.

How much coolant is in using in terms of litres/miles?

Has the car had a decent service recently?

Have the distributor cap/rotor arm been changed?

How many miles has the car done?

Apologies for all the questions, just trying to pinpoint the problem and hopefully you'll find out it's not the gasket.

If you do take the head off, you'll want to get it skimmed and pressure tested.

Post Tue Apr 12, 2005 9:55 pm

Thanks for the support guys.

The engine is 2.5 - standard apart from a 6-branch, larger TB and Zone chip.

No oil visible in the water or vice versa yet, but i understand that a gasket can leak just water into the cylinder without getting into the oil.

My car has never had any smoke from the rear before - now it's so bad that i've noticed traffic behind me keeping well back! Sometimes i cant even see out the rear screen because it's so bad.

I did have a leaking hose before, which i replaced with a new one. There are no visible leaks that i've noticed, but i will check again.

Haven't measured how much coolant i'm loosing, but roughly, i'm putting around a pint in every week, doing 125 miles.

I've changed the oil, oil filter, air filter recently - every six months or less before that.

Checked the dizzy cap last weekend - it was a bit corroded up, but after i cleaned it, there was no difference to the misfire.

The car is only just short of 140k miles.

To be honest, i got the diagnosis of leaking head gasket from the main man at my local BMW garage. Now many would presume that they're just making it out to be the worst to get the business, but i've had loads of good advice from him before and his theory seems to stack up. Having said this though, i'm always open to suggestions.

Post Tue Apr 12, 2005 10:53 pm

Pete, you're right. Even if the oil and water aren't mixing, it could still be the head gasket or head related.

I had terrible trouble with my car gobbling up water like nobodys business. There was no oil/water mixing and I was baffled. Eventually I got sick of topping it up and decided to put a new head on it. The old gasket looked perfect so I still don't know what the problem was to this day. My guess it was a hairline crack in the head.

Your problem is that you don't know if it's just the gasket or the head itself. It's very rarely just the gasket unfortunately.

With regard to skimming the head, you definately don't want to go doing that. People get the impression that you should skim a head when it's removed. This is NOT the case. Skimming will alter your timing and you'll need a vernier pulley to get it right. The term "skimming" means to remove a certain amount of material on the underside of the head usually used to raise compression.

What you'd need to do is remove the head, strip it, get it pressure tested and if it passes the pressure test then get the head "refaced". Refacing is different to skimming, only a tiny amount of material is removed, enough to get the surface completely flat and remove any contaminents. They usually use the lowest point of the head for refacing.

The trouble with head problems is that's a total unknown until it's all apart. I would suggest helping you out Pete but you have to leave the engine to go stone cold before attempting to take the head off which is a minimum of 6 hours.

Post Wed Apr 13, 2005 1:04 am

Pete if u need the head flashing and a de coke it what my dad does for a living. plus i need that tenner before thurs so i can collect that mat or something off Andyp mate from Bharat

Post Wed Apr 13, 2005 8:49 am

Adam,

Thanks for the advice - no less than i've come to expect! I'm due to have two weeks off work soon (pending arrival of our third baby any day now), so i'm hoping i can wangle a couple of days working on the car to save me a good few hundred quid. I need to sort out a list of bits i need though. Someone mentioned yesterday that you should change the cam belt and tensioner, but i only had this done last year, so is it worth changing again?

Simon - many thanks for that offer of your Dad's services - i'll almost certainly take you up on that. Cheers.

Can i drop this tenner off with you this evening or could we meet up somewhere? I'll text/phone you today sometime.

Post Wed Apr 13, 2005 10:37 pm

PeteE30Tourer wrote:Adam,

Thanks for the advice - no less than i've come to expect! I'm due to have two weeks off work soon (pending arrival of our third baby any day now), so i'm hoping i can wangle a couple of days working on the car to save me a good few hundred quid. I need to sort out a list of bits i need though. Someone mentioned yesterday that you should change the cam belt and tensioner, but i only had this done last year, so is it worth changing again?

Simon - many thanks for that offer of your Dad's services - i'll almost certainly take you up on that. Cheers.

Can i drop this tenner off with you this evening or could we meet up somewhere? I'll text/phone you today sometime.

Definately change the belt and only change the tensioner if there's any play or it spins freely. There should be some resistance to spinning slightly.

Post Wed Apr 13, 2005 11:31 pm

Check around the 5th spark plug for oil and water the condition of it as this is the one that runs the hottest and warps the head if it overheats.

Post Thu Apr 14, 2005 10:18 am

Pete,

Give me a shout, I know a really good guy who may be able to fix it with replacing the gasket.. depends where you are though, he's in hounslow if thats any use.

Post Thu Apr 14, 2005 8:19 pm

tommo320i wrote:Pete,

Give me a shout, I know a really good guy who may be able to fix it with replacing the gasket.. depends where you are though, he's in hounslow if thats any use.

That's not much good if the head is cracked. It needs to come off and be pressure tested. No-ones going to spend the money having a headgasket done without getting it pressure tested first only to get it all back together and the problem persists.

Post Fri Apr 15, 2005 9:53 am

When I had similar symptoms, he charged me 85 notes for a block and pressure test, luckily no problems how ever he did say if the head was cracked they have a special "thermo" treatment that fills the crack and solves the problem, treatment is about Ãƒ”šÃ‚£200, a lot less than replacing the head gasket!!!

Post Fri Apr 15, 2005 7:35 pm

Everyone i've spoken to so far on this - BMW and ex-BMW techinicians included - suggest that the gasket rarely goes and it's more often than not the head that gets cracked. I'll see when i get mine taken off and tested, but i've got another head lined up fearing the worst.

Post Fri Apr 15, 2005 10:06 pm

PeteE30Tourer wrote:Everyone i've spoken to so far on this - BMW and ex-BMW techinicians included - suggest that the gasket rarely goes and it's more often than not the head that gets cracked. I'll see when i get mine taken off and tested, but i've got another head lined up fearing the worst.

i agree its prob the head from all the stories i have heard.... sorry....