4.0 OHV top end redo

[Dantheman1540]

This filter is pretty cool, this was from my commute today. I cleaned it out and flushed the system again with fresh water today. Tomorrow I’ll go grab more evaporust and do another few days with that stuff. It seemed a little better today I did a long hard 3rd gear pull up to 4,500 then a little into 4th. It did get to halfway on the gauge during that but it recovered almost immediately which is a big improvement!

 

[MaicoDoug]

Been following, you're dedication is inspiring. Thanks for that. My favorite cleaner is what ever dollar store 'Tub & Tile" cleaner I can put my hands on. Currently after pulling the lower radiator hose for some in line temp sensor splicing, finally got a decent flush. So I kept up with it for a day after. Why not. Keep up the good work.

 

[Dantheman1540]

Been following, you're dedication is inspiring. Thanks for that. My favorite cleaner is what ever dollar store 'Tub & Tile" cleaner I can put my hands on. Currently after pulling the lower radiator hose for some in line temp sensor splicing, finally got a decent flush. So I kept up with it for a day after. Why not. Keep up the good work.

Thanks! I like experimenting and I very much dislike things getting hot when they shouldn’t be. I’ve driven a lot of crappy vehicles and never had such a bad cooling system.

 

[Dantheman1540]

Alright I might be reaching the end of this saga.

I flushed out my second rust dissolver flush today and swapped in a brand new heater core. My thinking was that the radiator was clogged with rust from the heater core. Therefore some rust dissolving stuff melting everything in the radiator would free that up and the new heater core would stop it from getting clogged again.

My findings are that the heater core wasn’t bad at all and I found no sign of rust even when it cut it in half with a grinder to inspect. Glad the new one was cheap and easy to install.

Also the rust dissolved seemed to have a lot of very small particles in it when drained but it can’t have done a ton because there’s still small chunks being caught in the inline filter.

I then filled the truck with water and went for some testing. It took a good bit longer to get warm but did within 15mins of blasting through sand get up to the L in normal. I then romped it even harder and the needle pointed just past the L but not to the H or Red hash mark. I then pulled over and whipped out my IR thermometer and pointed it at the thermostat housing. It only read 220*, I pointed at the radiator and it was around 180 on the hot side and much lower like 130-140 on the cold side.

Now these low readings somewhat confuse me but I realized that I don’t really know what the gauge parameters are. For example is N 140* and L is 220*? If that’s the case I don’t care if it reads L after a good thrash session. And maybe all this work was for nothing because I’ve never had the gauge go all the way to the H and red Hash mark. The strange thing is that the gauge never used to read past halfway except once or twice I remember I forgot to turn the Efan on.

So what do y’all think? Am I being overly trusting of the gauge and maybe it’s not over heating at all? Or should I continue this onslaught of flushing and component replacement?

 

[Dantheman1540]

One test away from ordering a TDI to fix the OHV overheating issue.

Just slapped a brand new radiator in and burped it real good. I let it idle for nearly 30 minutes with the fan OFF and it didn’t even get to the N in normal. Went for a rip down my sandy road and after two or three short runs never going above 3k but mostly staying around 2,500 It got very hot like usual, past the L in Normal. Did a good 10min cruise around the block and it cooled down a little but when I got home the thermostat housing was still reading 225* on my IR thermometer, which matches the gauge reading between M and A.

So clearly it wasn’t the radiator and I spent $300 for no reason. Also worth mentioning is that the water currently in the system comes out clear and clean, and the pre-radiator rust catcher filter is not even catching chunks. So the rust in the block or heater core or whatever problem is gone, but the radiator being clogged with rust isn’t the issue.

So I think I’ll finally go do the leak down test I should have started with and then come to the realization it needs the top end rebuilt or motor swapped.

Feel free to cry with me over my stupidity.

 

[Dantheman1540]

Unbelievably annoying is that the threads for the plugs are deeper in the head than the leakdown tester can catch. So I gotta go try to find some sort of adapter that’s got longer threads or I can’t do a leakdown test like I planned. These plugs are only a couple months old, and my god they look horrible. I’m definitely thinking this thing is toast. I run a fuel cleaner in every tank I never imagined they would look this bad.

 

[Shran]

Define horrible? Oil fouled, burned off, ?

My '94 is doing some frustrating things like yours... it will sit between the N and O if I just let it idle but if I drive it, it'll creep up a little higher and when I stop at a stop light, it'll jump up quickly to the L and then quickly recover and drop down to N-O... then repeat...as long as I'm at the stop light. If it's hot out and I have the AC on, it'll creep up to the A, sometimes L if I let it go... even while moving/at highway speed.

FWIW I spent some time with an IR thermometer and on my gauge cluster, the exact middle is about 200 degrees, A is 220, L is 230. I don't really consider 220-230 as being too hot, it's not boiling, but about 230 is the point where I start to worry.

Mine is just weird because the thermostat is clearly working but it's opening way late and it shouldn't be getting hot anyway, it just flip flops between really cold and really warm instead of settling somewhere. Additionally the heater does not work very well. I'm not going to blame the engine itself because I had a different engine in the truck, with a different thermostat, water pump, etc and it did the same thing. I'm fairly certain that I'm dealing with an air pocket trapped somewhere. That is really confusing to me because I've had 100% success burping air out of many of these trucks in the past and this one in particular is just fighting me for some reason.

 

[Dantheman1540]

Define horrible? Oil fouled, burned off, ?

My '94 is doing some frustrating things like yours... it will sit between the N and O if I just let it idle but if I drive it, it'll creep up a little higher and when I stop at a stop light, it'll jump up quickly to the L and then quickly recover and drop down to N-O... then repeat...as long as I'm at the stop light. If it's hot out and I have the AC on, it'll creep up to the A, sometimes L if I let it go... even while moving/at highway speed.

FWIW I spent some time with an IR thermometer and on my gauge cluster, the exact middle is about 200 degrees, A is 220, L is 230. I don't really consider 220-230 as being too hot, it's not boiling, but about 230 is the point where I start to worry.

Mine is just weird because the thermostat is clearly working but it's opening way late and it shouldn't be getting hot anyway, it just flip flops between really cold and really warm instead of settling somewhere. Additionally the heater does not work very well. I'm not going to blame the engine itself because I had a different engine in the truck, with a different thermostat, water pump, etc and it did the same thing. I'm fairly certain that I'm dealing with an air pocket trapped somewhere. That is really confusing to me because I've had 100% success burping air out of many of these trucks in the past and this one in particular is just fighting me for some reason.

Yours seems very sporadic much like air but these truck bleed very easy IMO. Have you done a heater core?

 

[SenorNoob]

You might have luck with a "spark plug non-fouler" to connect the compression gauge.

 

[Dantheman1540]

You might have luck with a "spark plug non-fouler" to connect the compression gauge.

I tried, the threads on what they had at my local store was too big.

I’ll find out what happened to this motor when I pull it out and tear it down for fun. I’m kinda over it, TDI it is!

 

[Shran]

Yours seems very sporadic much like air but these truck bleed very easy IMO. Have you done a heater core?

No but I flushed it from both directions and it seemed to flow pretty well. I think the heater issue is related to the temperature fluctuations. I've had bad thermostats affect heater operation before so it seems logical.

Not sure why this one is so hard to bleed. Usually my process for that is to start the engine with the radiator cap off, let it run for a few minutes while topping off the coolant, then when it's getting just a touch warm, idle up the engine to 2-3000RPM so that the water in the radiator gets sucked down and fill it all the way, then put the cap on, and let it return to idle. That has always worked perfect but not on this one.

 

[Dantheman1540]

Alright I wheeled this thing for 6 hours today in 95+ temps and got some interesting data. I can creepy crawl trails, blast down sandy roads, or drive highway speeds with the AC off and the truck stays ice cold. But during any of those scenarios if I turn the AC on within 5-10mins it starts to slowly heat up.

So this isn’t a motor issue but an AC issue?
Condenser getting hot? It’s only 2 years old, the whole system is 2 years old.

Maybe over serviced and causing condenser to get hella hot?

Maybe condenser needs a front pusher fan?

Condenser and rad too close together? Or too far apart?