Recently I installed a different motor in my DII. I used help from this board in the process, you guys are great! Thanks so much.

The truck runs great. I have a small issue, that I do not want to become a larger issue.

I have a slow leak in the coolant system (I can't find it). It is not being burned. I do not think it is a blown head gasket (at least I hope not).

The leak is causing coolant to run down both sides of the bell housing on the tranny. I can't seem to see where the leak is coming from. Any ideas?

156k on truck
110k on motor

Sruff

 

Valley pan gaskets can leak or anything that leaks on to the valley pan may exit the rear. Before taking off the intake manifold, rent/borrow a coolant pressure tester from the auto parts store, the vent cap spec is 20 PSI, so run it up to 5 PSI, stop and look, then 10, 15, 20 etc. Don't stop with first leak found. Should be able to hold pressure for 30 minutes, etc. May have to crawl under truck and look with a good flashlight while this is going on.

Sometimes the throttle body heater plate can leak toward the rear, but the both sides issue is a little different. Heater core pipes?

There is a chemical test for $50 you can buy for combustion gas in coolant. It will do like 16 tests, and may be worth doing to "prove" that the new motor does not have an HG problem, before overheating and bigger problems pop up.

 

I had one of the heater core pipes that got bent when I was changing that hose. It ended up with a slight flat side on one of the pipes coming from the firewall. It only leaked under high pressure. I removed the factory squeeze clamp, attempted to round the pipe a bit, and used a screw type hose clamp to better tighten against the not so round pipe.

With the coolant on both sides of the bell housing I am not sure this would be your issue, but sure would be easy to check before going to the valley pan gasket.

 

And if you look at this pix of a typical blown out the back HG, hard to think with light drip that it could go on both sides of the bell housing, it is a V-8 after all. Perhaps an inspection mirror and bright light may reveal more, if you can look in the valley. Maybe time to invest in an inspection camera, or hold a camcorder back there with the viewing screen at a sharp angle (can't get my fat head back there, but maybe a small camera).

 

borrow a preasure test from a local autoparts store, unless you have a gross leak you will find it very haed to find unless it under preasure. With 15-20 psi use a flashlight and a small inspection mirror, i would start at the valley gasket in the rear of the motor.

 

OK, just finished replacing the valley gasket. Truck is running... But the temp gauge is at normal conditions, and NO heat coming out of the vents... I was in the process of refilling the coolant (as per directions here), but with no heat: I imagine the temp gauge sensor is malfunctioning, or I have other issues. Any ideas?


sruff

 

On a D2, the heat gauge sensor is the ECU. The ECU reads the coolant sensor, uses that to work all kinds of magic, and also sends a signal to the gauge to stay at 9:00 unless too cold or too hot. Basically stay put so no one will complain. A more accurate way of looking at it is your code reader / scanner, where you can see the digital temp that ECU sees.

On a D2 hot water goes thru heater core whenever truck is running, there is no cut off valve.

That said, look over the attached flow chart for the plumbing. Notice that hot coolant goes down the top leg of the three legged thermostat, it goes toward water pump on the "arm" leg of the stat. Cooled coolant enters from the lower radiator hose. The top of the stat has small sampling holes in it that allow a little hot water to flow into the stat, warm it up, and cause it to open. This should happen starting at 180F, and fully open at 204F.

Sometimes the stats are bad and don't open (after market). Sometimes those little holes get full of gunk on a rad flush or major engine work.

Now you might have a blocked heater core (thanks to Dexcool), you could test by back flushing the heater core pipes (messy). You can also have a large air bubble in the system that is making part of the cooling system a steam room, instead of the hot bath it should be.

A lot of people struggle with refill of the D2, and some get better results by unbolting and raising the coolant recovery bottle. You basically have to make a mess, coolant needs to be coming out bleeder screw constantly, not in spurts. I wish they had a T with a stub you could attach a hose to and drain into a bucket with engine running to circulate the bubbles.

If line under coolant tank is kinked that can cause problems. If any of the small hoses are kinked, that can cause a problem. And some owners have found their heat core bypassed.

 

I was able to fix the issue of refilling the coolant. I had to rev the engine during the filling process, enough that forced the gases in the engine out the reservoir. I hadn't thought I needed to "push" it out, but after a few minutes of revving the motor as my teenage son added the coolant, and it began heating up, and belched the gas... like burping a baby...

Thanks guys.

sruff

 

Normally you would have no problem with a teenage son revving the motor (lol). Great job!

 

You said you had replaced the valley pan gasket. Did that fix your coolant leak issue?
i'm having, what I think is the same problem.
Since this thread is dead, i'm guessing that was the issue and it's now fixed.