How to: 4.0 OHV Refresh

[97Sandbox]

Okay, I was thinking pot of water and meat thermometer, see if it pops, but wanted to make sure I wasn't oversimplifying.

On the note of the muck in the reservoir, I noticed while I was letting the distilled water run through, brown gunk kept coming to the top of the radiator.

I'm fearing this is separate to the overheating issue, maybe a sign of a mildly blown head gasket. Any thoughts?

 

[Lee's Automotive]

Okay, I was thinking pot of water and meat thermometer, see if it pops, but wanted to make sure I wasn't oversimplifying.

On the note of the muck in the reservoir, I noticed while I was letting the distilled water run through, brown gunk kept coming to the top of the radiator.
View attachment 432221
I'm fearing this is separate to the overheating issue, maybe a sign of a mildly blown head gasket. Any thoughts?

That looks like crap literally something isn't right at all

 

[Pete Deering]

Pulled the thermostat and I'm about to flush with distilled water until the rusty debris is gone. Does anyone see anything odd with the thermostat?
View attachment 432218
Is the rust line an indicator of air trapped in the system?

View attachment 432219
Engine side looks fine to me. Not sure if there's anything I should check.

Don't see the vent hole

 

[Pete Deering]

Okay, I was thinking pot of water and meat thermometer, see if it pops, but wanted to make sure I wasn't oversimplifying.

On the note of the muck in the reservoir, I noticed while I was letting the distilled water run through, brown gunk kept coming to the top of the radiator.
View attachment 432221
I'm fearing this is separate to the overheating issue, maybe a sign of a mildly blown head gasket. Any thoughts?

? Is it from a sealant, coolant or head gasket?

 

[allmyEXes]

I recently refilled my '92 OHV through the heater hose attached to the engine. Previously an engine flush kit was installed, so I took the cap off and stuck a funnel in the T fitting and refilled the engine that way. No air bubble, no overheating.

 

[97Sandbox]

Don't see the vent hole

I was wondering about that. I thought these Stant thermostats were the good ones to have -- can anyone recommend a part number for a better one with a vent hole?

? Is it from a sealant, coolant or head gasket?

No clue. I've never added sealant and the coolant was fresh as of two months ago. The brown sludgy stuff floats on top of the water like oil would, it looks like mud, and there seems to be a trace of it throughout the cooling system. There was also a lot of built up crud in the cooling system when I first bought the vehicle (it had been pretty neglected) so maybe it was trapped somewhere like the heater core and it's just now coming out with these additional flushes. Or the head gasket burned through somewhere when it got hot the other day and now there is oil getting into the coolant...anyone's guess for now.

I'm going to do one or two more flushes of the whole system (with thermostat removed) and see if the gunk keeps coming back.

 

[410Fortune]

pretty nasty, hoping its not a blown intake of head gasket

 

[97Sandbox]

pretty nasty, hoping its not a blown intake of head gasket

Me too. Not sure how the intake gasket could have failed so quickly, I was very careful to clean the heads, valley, and manifold during reassembly.

Head gasket condition is questionable at best. It sure would suck to tear it all back apart -- almost wish I'd gone ahead and done the head gaskets when I did everything else. Still, I think that's separate from the root cause of the overheating.

 

[97Sandbox]

Back to the thermostat, is this Motorad unit with the little brass barb what I should switch to in order to alleviate the trapped air issue?

 

[96AWD5.LOL]

You can buy that OR drill an equivilent hole into the one you have assuming you've tested its not sticking.

 

[410Fortune]

You can also remove the upper radiator hose from the radiator hold it up high and pour in a coffee pot full of boiling hot water it will open the thermostat and release any trapped air

I can’t believe they still sell a thermostat without the small bleeder

 

[97Sandbox]

Turns out it's very challenging to keep water above 198F when transferring from coffee pot to container with thermostat. Jury is out on that test.

I've continued flushing and a concerning trend is emerging:

Off to pick up a compression tester...

 

[Lee's Automotive]

Turns out it's very challenging to keep water above 198F when transferring from coffee pot to container with thermostat. Jury is out on that test.

I've continued flushing and a concerning trend is emerging:
View attachment 432283

Off to pick up a compression tester...

Hook up a water hose to a flush adapter and let it run for a while

 

[Lee's Automotive]

Not the vehicle the hose leave the hose running

 

[97Sandbox]

Compression test looks good. Back to flushing I go!

Starting to think the oily sludgy stuff was trapped in the heater core or something and now that it's loose I just need to flush it all out.

As for the overheating, I'm going to go ahead and get a thermostat with the bleed hole. Bleed hole points up upon install, right?

 

[donalds]

Bleed hole points up upon install, right

Yes

 

[97Sandbox]

Hook up a water hose to a flush adapter and let it run for a while

I tried this and it seems to have eliminated the rusty colored water situation. When I finally drained out the hose water it had a slightly yellow tinge, but much improved from the previous flush.

Topped back off with distilled water and let it run. I'm still getting oily sludge at the radiator. Is there somewhere the head gasket could be blown where oil would get into coolant but cylinders still seal and no coolant gets into oil? Otherwise I don't know where the sludge keeps coming from.

 

[Lee's Automotive]

I tried this and it seems to have eliminated the rusty colored water situation. When I finally drained out the hose water it had a slightly yellow tinge, but much improved from the previous flush.

Topped back off with distilled water and let it run. I'm still getting oily sludge at the radiator. Is there somewhere the head gasket could be blown where oil would get into coolant but cylinders still seal and no coolant gets into oil? Otherwise I don't know where the sludge keeps coming from.

I'm starting to think trans cooler in the rad is leaking into the rad and miking with the coolant

 

[97Sandbox]

I'm starting to think trans cooler in the rad is leaking into the rad and miking with the coolant

That's a good line of thinking, except my Sport has no trans cooler, it's a manual.

 

[fast_dave]

Just askin' since I haven't seen it mentioned.

You have an oily sludge (post 161 picture) coming up to the top.

With that in mind, have you pulled the dipstick or better yet drained the oil into a plastic jug to see if anything is going on down in the bottom of the oil pan?

Loss of oil or separation line (oil/water) or milkshake?