Oily sludge and its eventual destruction (a work in progress)

[jbg]

Thanks for the reply. I have not driven the car on any real distance as the gauge freaks me out and I opt to keep things very local. I drained the oily water-soap today from the radiator. It wasn't much liquid. I suppose the thermostat didn't open. Here is what I was assuming I would do to get things cleaned out:

1. Drain.
2. Fill with two cups of detergent and the rest water.
3. Start the engine with the coolant cap off.
4. Let it idle until the water level in the overflow tank drops. I assumed this to mean the thermostat opened and is pulling water/detergent into the block.
5. Top-off the overflow tank and allow the engine to continue idling. Monitor for engine temperature.
6. Repeat.

Is my process flawed? Silly question, but if I keep my expansion tank cap off will the thermostat ever open? Does the thermostat need both temperature and pressure to function properly? I've never thought to think about this until now.

Oil is coming from the passenger-side (US-spec) between the cylinder head and the block. Near the front of the engine underneath the exhaust manifold.

[anders]

I have had two D24t's valve covers leak at the front bearing cap. It leaked down the front of the cylinder head and followed the head gasket, making it look like the head gasket was leaking, more so on the 240 then the 740 as the engine is slanted more to the passenger side.

[ngoma]

See my comments in bold italics:

Originally Posted by jbg

1. Drain.
2. Fill with two cups of detergent and the rest water.
   Undo the top small hose from top port of the IP thermostatic actuator, keep filling reservoir until coolant (no bubbles) runs from that top port of the TA. This will help avoid trapped air bubbles. Reattach the hose.
3. Start the engine with the coolant cap off.
4. Let it idle until the water level in the overflow tank drops. I assumed this to mean the thermostat opened and is pulling water/detergent into the block.
5. Top-off the overflow tank and allow the engine to continue idling. Monitor for engine temperature.
6. Repeat.

Is my process flawed? Silly question, but if I keep my expansion tank cap off will the thermostat ever open?
Yes, but might not open for a long time just by idling (diesels in general).
Does the thermostat need both temperature and pressure to function properly? I've never thought to think about this until now.
Tstat does not need pressure to operate. Pressure helps raise the boiling point of the coolant. The cap allows the system to build pressure, up to its release point. Many like to use the 75 kPa caps to lessen the risk of blowing old heater cores, coolant hoses, radiators, etc.

[jbg]

Originally Posted by ngoma

Undo the top small hose from top port of the IP thermostatic actuator, keep filling reservoir until coolant (no bubbles) runs from that top port of the TA. This will help avoid trapped air bubbles. Reattach the hose.

Oh yes, of course. I should have read my Green book! I never detached that hose so there must be a large air bubble in the system. That would explain a) the gauge reaction, and b) the small amount of fluid I drained / added. I bet once I loosen that hose the expansion tank level will drop as air is bled and more fluid is pulled in. Thanks ngoma!

[jbg]

When drained some additional oil poured out. This time I removed the injection pump thermostat hose to allow the system to burp. Filled the system and ran the engine. Eventually the idle speed began to slow as the wax thermostat began to move, at least it was getting the water/soap! The level in the expansion tank dropped about two inches and I added water at that point and shut her down. Tomorrow I'll drive the car a bit and nervously observe the temperature gauge.

On the flip side I've got this drain/re-fill process pretty streamlined.

[jbg]

I drove the car around the neighborhood for about 10 minutes or so. The temperature gauge acted normally, no erratic behavior or other gremlins to speak to. In my previous post I mentioned that the water level in the expansion tank dropped about ~1.5 inches and I took that to mean the thermostat had opened and pulled water in. After driving the car around I popped the hood and checked the hoses. The upper hose from the radiator to the cylinder head was very warm, even hot to the touch. Whereas the bottom hose from the thermostat to the lower radiator opening was slightly warm. Finally the hose leading to the injection pump wax thermostat housing was also warm.

Why wouldn't the lower radiator hose be hot like the upper? What way does coolant flow in the engine? Does coolant flow from the engine to the top of the radiator (hot), is cooled by the radiator, and exits from the lower radiator opening and through the thermostat? My goal here is to make sure the thermostat is opening, it must be as I didn't see any signs of overheating.

As a side note both my Nissen radiators I bought from eBay arrived yesterday, they're very nice quality and the price cannot be beat!

[745 TurboGreasel]

All engines pull from the lower hose so they have some cooling till the last drop of coolant is gone. You may have to block the rad with cardboard or something if you want to heat the whole system without running full load for awhile.