Andy A

Greeting all first time poster with some questions about a coolant leak. Have done some searching and come across some good ideas but not sure have hit upon my problem.

1994 SR5 v6 3VZE engine. Have had truck since new. Approx 200000 miles. Headgasket recall done at 100000 miles(short block was replaced at that time also).

Have a coolant leak coming somewhere from the passenger side rear. Looking up under the truck it looks to be coming from up around the head possibly the lower corner, but is hard to tell as it maybe channeling down to that area. Will drain the radiator empty in a few hundred miles.

My thoughts were
1) water block gasket at the rear of the intake(hoses going into water block are all fine not leaking)
2) a hole/crack in bypass tube
3) Intake manifold gasket leaking at passenger side rear corner.
4) headgasket (No coolant in the oil and no oil in the coolant).

Upper intake is removed to try and get a better view but still nothing conclusive.

Andy

sb5walker

There's a little upside-down U-shaped hose attached to the water outlet in the rear that gets cooked by the exhaust crossover and often develops leaks. Might want to check it out:


(thanks to clocklaw for the pic)

Andy A

Hose appears clean and dry. In searching, quite a few people were having problems with that hose so it was one of the first checked.

sb5walker

Has the coolant ever gotten rusty? That's a sign that coolant was either left in too long or was mixed with a different coolant type or with tap water, and became acidic. There are several steel pipes in the cooling loop that can develop pinhole leaks if that happens, including the pipe that the U-hose is attached to, which runs forward under the intake manifold to attach to the back of the water pump housing. There's at least one coolant line in the cluster of steel (mostly vacuum) pips that is bolted to the plenum. When I let my coolant get rusty, the coolant pipe in that cluster developed a pinhole leak.

Andy A

So far no rusty coolant, but still doesn't mean one of the metal pipes have not developed a crack or hole. As you mention the pipe that the j or u hose attaches has got my curiousity peaked as it is right in that area.

I guess my next step is to pull the lower intake which I'm not looking forward to. Haven't quite figured out whether or not removing the fuel rails is required yet.