4.0l freeze plugs in rear of block?

dennis461 · Jun 24, 2016

Are there freeze plugs in rear of the block, 1997 4.0l?
Just put new head gaskets on and have a leak showing up at bottom of bell housing.

Figured one of the heads was leaking, but cannot seem to find where the water is coming from.

alwaysFlOoReD · Jun 25, 2016

I found a pinhole in one of the frost plugs in the rear of the passenger head by pressurizing the system to 30 psi. I bypassed the radiator because I didn't want to blow a hole in it. I used a heater hose that had a twist cap. I drilled a hole the same size as the hole in a tire rim for the air valve. I then used a tire valve in the cap and pressurized. If it holds pressure overnight you're golden. There are frost plugs hidden by the trans but some are not for the cooling system. One would be cam and a couple small ones for oil passages.

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dennis461 · Jun 25, 2016

anyone have a pic of rear of engine?

I thought water was dripping from above the starter, but could not see where.
Started to remove starter to get a better look.
water came out as soon as I loosened the bolts.
Bendix is soaked.

So either a freeze plug in rear of engine or cracked block.

The job started with a #3 misfire and failed air pressure test on that cylinder.

RonD · Jun 25, 2016

The 4.0l OHV are cast block and heads but use an aluminum lower intake.
Each corner of that intake has coolant, passenger front and drivers rear are the pass thrus from head to head
When you mate two different metals and then add a moving liquid you get electrolysis, which eats away at the softer metal, intake in this case.
A leak at a rear corner of lower intake could run down into bell housing/starter.

Might not be it just giving you the heads up about it.

There is one freeze plug in rear of block, drivers side, so above starter motor.

Picture of the rear of 2.9l(4.0l OHV is same block) in this thread: http://www.therangerstation.com/Magazine/January2011/FM146_to_M5OD.shtml

Starting about 1/3-1/2 way down the page.
Also a Cam shaft plug and there is a smaller plug but not sure if that is oil or coolant

dennis461 · Jun 26, 2016

We took intake top plastic off to get a better look at things.
Pumped up the radiator with 19 psi.
No leaks, pressure help u solid.

Reassembled everything and started it up.
Water came out after about two minutes.
Pretty certain its inside the bell housing.
Leaking when hot , not cold, smells like a cracked block...

4.0l freeze plugs in rear of block?

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