Preemptive HG sealer ?

Just picked up a 93 4Runner v6 with 150k , maintenance up to date but am worried the HG is a ticking time bomb . I know many have used blue devil to fix a bad HG and was wondering if there is any justification to adding it now to avoid breakdowns in the future. Will do a compression test this week and hoping cylinder #5,6 are okay . Also considering having an exhaust shop delete the crossover pipe and remove that added heat source. Thanks y’all !

 

Adding it won't help on a good head gasket.

The way these things work is that as the coolant leaks into the cylinder from a cracked HG, the hot combustion gases cause the additive to clump up plugging the leak. If there is no leak, no clumping.

The additive can cause other potential issues, so best bet is to only use it when there is a problem.

 

If i'm not getting any tail pipe smoke, what's the best way to check the health of the engine? compression test? I want to be as on top of it as possible, thanks

 

Yes. Dry and wet Leak down tests.

Examine all spark plugs and make sure they look normal. Plenty of online spark plug charts to illustrate that.

 

You can get rid of the crossover in the exhaust. This will help with heat on the backside of the motor. Most 3.0 headgaskets blow either at cylinder 6 or 1. There is a lot of theory the crossover is the culprit. There's a ton of threads on other forums about it if you want to read about it. I have a 92 pickup with the 3.0. Headgasket went at like 290k. I rebuilt the motor. When I did I used ARP head studs and got rid of the crossover.

 

Is it possible to do the crossover mod with the engine in place or do many parts need to be removed in order for someone to fabricate exhaust

 

The engine does not need to be removed.
Google toyota 3.0 crossover delete. There's a bunch of kits. I made my own so I don't have any reccomendation on kits.

 

Just did compression and have basically 150psi at every cylinder , does this sound okay?

 

I think 170 is what a new from the factory 3vze would measure. 142 is considered low if i remember correctly. 150 is on the lower end of the spectrum but the fact that they all measured so closely wouldn't indicate a specific problem. Sounds like you have a well worn in motor.

 

^Right, the thing you're looking for with a compression test if you suspect head gasket failure isn't a specific cylinder pressure, but a cylinder pressure that is inconsistent with the other cylinders. If there was a head gasket failure, you would expect one of your cylinders to have a significantly lower pressure than the others.

 

Wet or dry?

Wet will show it higher and depending on the amount of the jump, it will give you some indication as to how worn the engine is.

150hp on a dry compression test is fine on an old motor.

 

It was a dry test