Head Gasket Repair

[Joshua2705]

Hi, I got a 2000 740iL and I'll be attempting to replace the passenger side head gasket. I have the cam/crank setter tools and a fel pro head gasket kit along with the head gasket itself and head bolts. Can anybody give advice as to what else I should fix/check while I'm in there and if anybody is familiar with not messing up the timing on the cam phasers. Thanks.

[jimoreno]

If guides have never been done (or have no records) then do them and also change the other head gasket. No reason to repeat this again in the near future (although it might not happen I would not try to get away from doing it, peace of mind).

[CPHES]

Head gasket failure is rare in this engine. Are you sure that is the issue? Timing chains, valley pan, water pump, there are a bunch of items that should be looked at. Can you tell us what happened?

[Joshua2705]

Head gasket failure is rare in this engine. Are you sure that is the issue? Timing chains, valley pan, water pump, there are a bunch of items that should be looked at. Can you tell us what happened?

Bought the car really cheap because the owner (who is a mechanic) told me the head gasket was blown. There is coolant getting into the crankcase as the oil is chocolate milk. Any other things that could cause this?

[CPHES]

Sounds like the head gasket - have you considered a new / used motor that is known to be ok?

[R Shaffner]

I'm always reluctant to believe what the seller says, mechanic or not. Even if they're honest, they might not really know, or know all the problems until they've done more work.

Before doing anything I'd assess the situation as much as I could. I'd start with a compression test of all cylinders, to see what you got. (Getting another engine or walking away might be better options, depending on the condition of that one.)

Have you heard the engine running, or driven the car to ID other potential issues? If the compression test is good enough to proceed, I'd start the car and prob try to drive it in a safe way. That is, I'd change the oil and filter (with cheap conventional oil), and change the coolant (using the proper bleeding process). I'd leave the coolant cap off or loose so the system would NOT pressurize. And if you found a cylinder or two with poor compression (like where the suspect gasket is blown), I'd leave those coil packs disconnected so you don't get a spark in those cylinders.

Then I'd try to start the engine to see how it did, if it sounded OK (taking any roughness from disconnected coils into account). If OK, then I'd drive it to see how the rest of the car performed on a normal road test. (I'd take a real short drive first and stop to check the oil and coolant levels. If things kept looking OK, I'd feel comfortable taking longer drives to check the rest of the car out.)

So long as you have a decent blend of antifreeze and don't stress the engine with heat (don't drive too hard or sit too long in heat with the AC on), it should do OK with the coolant cap loose on short drives. On longer drives I'd set the heat on high to keep the coolant from boiling too much. (That car has a high temp MAP thermostat.)

And of course, I'd also check the oil and coolant levels to see if one is dropping or getting transferred to the other, whether steam or smoke came out the exhaust, etc.

If the rest of the car is good enough, then I'd proceed with repairs that make sense, or getting another engine if that seems like a better option.

Good luck!

P. S. Before cranking the engine for the compression test, I'd pull all the plugs. You'll want to examine them of course, for fouling etc. I also would want to see if coolant has been sitting in any cylinders, and wouldn't want to crank the engine while any significant coolant is still there.