replacing v8 head gaskets, any secrets I might benefit from?
 

Gentleman:

Ihave a few ques. concerning replacement of my head gaskets: 82 380 sel 121k. Recently done a singl-to dble w/o diff; car ran/idled excellent. Then, I noticed oil leaking under the intake. I removed the intake to find a pond of oil. Iam going to replace both head gaskets. Are there better gaskets than others regarding brands? Also, can you use a gasket sealer in conjunction with the gasket? I removed the intake in one piece too; Would it be advisable to replace the rubber grommets that attach the lower unit, or leave it alone. Another thing. Being that the heads are removed at that time, can a reputable machine shop replace the guides and ck. the valve lash. There never was much valve noise before I tore it down except a slight ticking on the pass head. Can the thrust pieces be cked while heads are off? The engine never seemed to burn oil and has plenty of power. Something else; I plan on replacing the fuel-injector o-rings too. The injector came aprt in two pieces. Can they be cleaned and w/ what do I use? Finally, I noticed in the service cd that there are special dowells used in the heads to remove to air-injection sys. I have removed the pump earlier w/ the hoses. I already passed the emission w/ flying colors and want to mod. the heads while they are off. Sorry for the long thread. Any hints or other info making this challenge smoother will be greatly appreciated. I would have gotten rid of this car if it wasn't for this site and the pros who post in it. Thanks-a-bunch!! les :eek:

Are you SURE the oil leaking isn't the valve cover gaskets? Oil leaking from the head gaskets on an M117 doesn't ring a bell for me.

If you have the manifold off, replace the rubber seals, they are cheap. Ditto for injector seals, although they are not a problem

I'd only do valves if you have some evidence they are in need of repair -- normal time to valve job with decent maintenance is 200,000 miles on these engines.

However, if the cams show signs of wear, I'd do a complete valve job now rather than piddle around and end up taking the heads off two or three times.

You have hydraulic tappets and will have to check them the book way. I have mechanical tappets, so can't help you much there.

Peter

Thanks Fred!
The engine is a 116 and the oil is definitely coming from the rear end of the head gasket. I have not separated the upper/lower intake yet however, the rubber grommets look ok. I just unbolted the exaust manifolds this morning; do they come apart in two sections when the spring clamps are released. They seem reluctant to separate very far from the heads. I wonder if I should just start unbolting the heads and when I pull up on them, the bott manifold bolts will clear.

unless you know the intake has been resealed, do it anyways. check the throttle switch, although i strongly suggest you replace it, too. you have to pull the intake again when it's bad. a set of injectors, holders, seals and hoses, all the vacuum leaks are gone and the new injectors will make a difference, too. usually 2-3 mpg on the highway. good luck, chuck.