Ok, so I'm going to be replacing my head gasket this spring and was wondering what all I should do besides the gasket and bolts? I'm at about 125k so would it be smart to just take the whole engine apart and get new main bearings and such? Any ideas of what I should do while I have the engine apart?

What's needs to take place/be replaced to replace piston rings? Also, would it be a good idea to do the timing chain, rails, and tensioner?

Also, does anyone know what comes in the head gasket set on pelican parts?

It's a 95 m42 w/a 93 intake manifold and sensors.

Thanks in advance,
km

To answer any of that we'd need to know why you are replacing the head gasket.

Do you have a known headgasket leak? And if so did it contaminate the oil with coolant?

There is a small leak I assume since there is water in the dipstick tube and on the oil lid before it evaporates at running temp. I need to do a leak down test, but I don't drive it during the winter months, so that'll have to wait till spring. I'm just wondering what all everyone replaces when they do a hg replacement

km

If there is water on the dipstick, the main bearings are at risk. I'm an ex 944 owner, ask me how I know. ;)

When you remove that head, take it to a reputable automotive machine shop and let them do a valve job on it. This will include checking valve guides for excessive wear, checking the head for warpage, checking for cracks, complete vat cleaning, replacing the valve guide oil seals (take the seals with you from your head gasket set), grinding the valves and seats, etc. Stuff you can't do at home.

This would be a perfect time to do rings and bearings also. Don't forget to carefully hone those cylinders out if you do the rings. Also, replace the freeze plugs.

Definitely do the timing chain/sprockets/guides/tensioners.

My .02 worth!!

There is a small leak I assume since there is water in the dipstick tube and on the oil lid before it evaporates at running temp. I need to do a leak down test, but I don't drive it during the winter months, so that'll have to wait till spring. I'm just wondering what all everyone replaces when they do a hg replacement

A bit of water around the cooler parts of the engine (dispstick, oil fill cap, valve cover, etc) isn't unusual if the your driving pattern doesn't involve 2-3 highway speed (60-70mp) trips each week of at least 15-20 minutes. That moisture is the result of combustion product blow by and doesn't necessarily mean that you have a head gasket leak.

The symptoms of a headgasket leak would include:

1) Mysterious random overheating
2) An inexplicable loss of coolant
3) A need to purge the cooling system of air for no apparent reason
4) The presence of a milky emulsion in oil drained from block
5) Clouds of white smoke from the exhaust
6) Missfiring or failing a compression test

If you don't have any of those symptoms you may not need to replace the head gasket.

plain the head and use a copper spray on the gasket

9 times out of 10 when you've blown a head gasket, you've warped your head. I'd definitely have it checked. You will probably have to have it milled.
The good part is you boost your compression :)

Deacon

never knew it was going to be so much work, maybe i should just rebuild my other motor for a turbo, price is starting to rack up on this one.

How much does it cost to have the head done at a machine shop?

Another question for everyone--when I am cruising ~60 down a long steep mountain and don't gas it, but instead let the engine brake, about the bottom of the hill, the check engine light blinks on, until I touch the gas pedal. Could this be from the head gasket leak causing it to be lean mixture? This is only on mountains with say a 8% grade or more.

HEY !
Apologies for shouting but check your PCV tube to see if it is clogged with blowby residue.
If this tube is blocked you will never draw the moisture and condensation out of your engine even when you are up to temp.
Don`t worry about the condensation that has been in your engine up til now.
If this engine isn`t knocking down in the rods and crank then just drive the thing, these BMW engines are very well built in regards to the cranks and rods.
If you aren`t losing coolant then I would not be so quick to pull the head.

The engine warning lamp illuminating under the conditions you describe may just be what is called a "spurious" or false trouble code indication. The older OBD 1 cars had relatively primitive software and processing capabilities. In a sense, with the conditions you are giving the car, you are "tricking" the computer and it doesn`t have an answer for the conditions which you have created. Ignore the light unless you are getting a "hard" code, trouble code when you access your trouble codes from the ECU. If you have a hard code stored in the ECU you can begin to initiate a diagnostic search if necessary.
andrew

Thanks, everyone. I'm most likely just going to do a rebuild anyways to be safe.

How much does a typical leakdown test cost?

Where in Virginia are you located? I know a great shop in Alexandria, Virginia.

You can do a leak down test on your own, just go to any car parts store and buy the kit. Just pull a spark plug and insert tool.

Having a head milled should be around $50.

You can do all the stuff mentioned, but in all honesty, I'd just have the head milled and install.

Thanks, everyone. I'm most likely just going to do a rebuild anyways to be safe.

I wouldn't re-build the engine if it wasn't necessary--thats a lot of unnecessary work and hassle for a blown headgasket. I would do a compression test and if you're way below specs, then I would look into a rebuild... (note that if it is a bad headgasket, you will find a cylnder or two lower than normal.) So, you'll have to replace the headgasket, and then do the leakdown/compression test to see if you have bad rings--kind of a catch-22, but my guess is that you just need to replace the headgasket.

Anyway, put on better headgaskets than stock, have heads milled, and that's about it. While other things mentioned would be 'nice', they are not necessary and I wouldn't do it. I would have them check out the valves while they had the heads, though.

guarddog,

you mentioned in this thread a machine shop in Alexandria? Tell me more, I'm re-doing an M42 head and need to have it inspected/milled.

cheers!
John

The symptoms of a headgasket leak would include:

1) Mysterious random overheating
2) An inexplicable loss of coolant
3) A need to purge the cooling system of air for no apparent reason
4) The presence of a milky emulsion in oil drained from block
5) Clouds of white smoke from the exhaust
6) Missfiring or failing a compression test

If you don't have any of those symptoms you may not need to replace the head gasket.

more like symptoms of a cracked head, too!

A bit of water around the cooler parts of the engine (dispstick, oil fill cap, valve cover, etc) isn't unusual if the your driving pattern doesn't involve 2-3 highway speed (60-70mp) trips each week of at least 15-20 minutes. That moisture is the result of combustion product blow by and doesn't necessarily mean that you have a head gasket leak.

The symptoms of a headgasket leak would include:

1) Mysterious random overheating
2) An inexplicable loss of coolant
3) A need to purge the cooling system of air for no apparent reason
4) The presence of a milky emulsion in oil drained from block
5) Clouds of white smoke from the exhaust
6) Missfiring or failing a compression test

If you don't have any of those symptoms you may not need to replace the head gasket.

I agree. Some condensation is normal.