To replace the head gasket or....?

[byrd_hntr]

The PO on the 79 fj40 did some funky stuff to my rig and I am slowly working them out. The rig has always ran a little warmer than I would have liked and there is a pin hole in the top of the radiator (put there purposely I think). The old I have a blown head gasket and don't want to admit it trick....

I was doing some general maintenance stuff the other day and I noticed the typical buildup on the plugs that suggest water getting into the cylinders. I also get the typical white smoke when shes cold but it goes away once the engine is warmed up. So it looks like its time to do a head job.

My question is should I just do a gasket swap or should I go all the way. Also what else should I do while Im in there? Im planning on a new H2O pump and T-stat. But is this a good time to do anything else? How about a RV cam?

The engine has ~115K on it and compression is decent, between 125-136 psi on all cylinders.

 

[SteveH]

I would not start a head gasket replacement until you do some more testing. 'Buildup' on the plugs is often due to oil or fuel additives, or from driving it in town extensively. If the compression is that high, and even, that doesn't point to a head gasket.

I would pressurize the cooling system for some period of time and see what the pressure drop over time is. Alternatively you can pressurize each cylinder and see if you see bubbles in the radiator neck. I would solder the radiator hole shut and see how the truck heats/runs/drives with a pressurized cooling system.

If it misses badly when started cold and blows out a big white cloud for some time, then you probably do have a bad gasket, but as written in your posting, it doesn't sound that bad.

 

[byrd_hntr]

Yes, I agree a Pressure test is probably the way to go. Ill have to see if I can get the hole sealed up on the radiator.

That's a good idea to test each cylinder.

Ive seen enough blown head gaskets that my gut feeling is that's the problem. But who knows stranger things have happened.

 

[1973Guppie]

do you have oil in the coolant, you should be able to get a good idea if there is a bad hg from a compression test?

 

[byrd_hntr]

No oil in the coolant, and the compression test is fair, between 125-136 psi on all cylinders.

I think I am going to plug the hole in the radiator, (Ill try soldering it tonight) and see if the overheats or not.

Its a little on the back burner right now cuz I am doing the front axle rebuild on another rig.

 

[Mark W]

That compression says "No blown headgasket".

"Buildup" on the plugs is not a sign of headgasket failure that I have encountered. And you make it sound like you have this buildup on all, or at least more than one cylinder. That is not a sign of headgasket problems.

Steam (not smoke) is always gonna be present in a cold engine. Smoke has nothing to do with head gasket.


Mark...

 

[KillerPea]

That compression says "No blown headgasket".

"Buildup" on the plugs is not a sign of headgasket failure that I have encountered. And you make it sound like you have this buildup on all, or at least more than one cylinder. That is not a sign of headgasket problems.

Steam (not smoke) is always gonna be present in a cold engine. Smoke has nothing to do with head gasket.


Mark...

x2. Steam at cold startup is actually a sign of a decent running engine.....one of the by-products of complete combustion is H2O.
In my experience, Cruisers rarely blow headgaskets or warp heads. If your experience is in other vehicle lines or brands, then the natural tendency is to assume the worst. However, with a Cruiser, I would assume the best and just fix the radiator.