I just read thru this whole thread and thought someone was talking about my Jeep.

I have a 1997 Wrangler with a swapped in 5.2 V-8. Ever since I installed this engine it has never ran totally like it should. After about a year I noticed that I was burning oil. So I did the Hughes plenum intake repair and after that I started having over heating issues. They are pretty much what the OP has posted. I over heat any time I am trying to climb a hill or really work the engine. I have replaced the t-stat 3 times, replaced the water pump twice and the 2nd time to a Flow Kooler water pump.
I think it is a blown head gasket that doesn't show up until the engine gets warm.

I hate to see someone else going thru all this but it is also nice to know I am not alone. Now if we can all just figure out what the heck is going on I'll bet a bunch of us would dance a jig.

 

1) What does your oil look like?
2) Have you done the hydrocarbon test with your coolant yet?
3) What temp does yours go to?

I 4x4 weekly. I have a 195 stat and run about 195-200 at 2.5k-3k rpms. This is normal to me though. Since I had this truck brand new it has been running those temps. When the rpms run 2k or less I am around 180-190. On the highway I am always at 180. Stop and go city diving (sux!) around 195-200.

 

No I have not done a hydrocarbon test on my coolant. My oil looks fine and the level stays the same.
I can't drive down the feeway at 65 or 70 MPH as the engine doesn't have the power to hold it. Before I fixed the plenum gasket I use to run at 200-210* all the time with no issues. I even went so far as to install an aluminum radiator and it helped but I still overheat. My electric fan was running so long it burnt the wiring up.

I am going to take the top end apart next month and install new heads, cam, roller rockers & intake manifold and see what that does.

 

?? The stock Dodge radiator is aluminum.

 

No that is why I said "I went so far as to install an ALUMINUM radiator". It is an aftermarket radiator built special for a Jeep with a Dodge engine in it and is running a Spal fan and fan controller. Nothing on this Jeep is stock anymore.

I had a 2 row radiator in it to begin with that worked great for the first 2 years. As I said it wasn't until I did the plenum gasket that I started to have overheating issues.

 

I'd take the intake back off and make sure the gaskets are in the correct configuration. What brand did you use?

 

^^ Agreed. They could be on wrong and a coolant port (or two) is blocked. Go back to the beginning when the problem manifested.

 

I have had the intake off twice since the problem started. I thought the same thing at first. The Dodge intake gasket is pretty much idiot proof there really isn't any way you could put one on wrong or cover any coolant passages. Without typing a book just believe me when I say I have tried everything and anything to figure out why this darn thing won't cool right. And I have thrown more parts at it than I ever should have. I have had my PCM reprogramed, bought a spare PCM and ran it, install the Flow Kooler water pump, and even installed that aluminum radiator. Nothing has worked which is why I am going to take the top end apart. I want to build a 408 for my Jeep but just don't have the funds right which is why I am just doing the top end.
In the next year I hope to build a 408 short block and then transfer all the new parts I am putting on my 5.2 onto it.

 

First off I want to say sorry to the OP for getting in on your thread and taking it over. Hopefully what we figure out will help both of us.

Ok my local NAPA didn't have test strips but had the bulb type tester. So I warmed my engine up yesterday with the rad cap off. I filled the radiator as it was a little low. Then when I was sure the thermostat was open and I had good flow I was getting ready to put the tester onto the radiator when it started spewing antifreeze out. Now when I say SPEW I might want a different word. It was like a violent vomit the stuff blew maybe a foot in the air. It kept doing this for 30 seconds and when it stopped you could see steam being blown out the radiator like crazy. I tried to put some fluid back into the radiator but anytime it got close to the being full again it would just spew it back out. So with this tester I was suppose to fill it with a liquid and then place it in the radiator neck. So I did but there was so much pressure coming out and it was so hot it was boiling the liquid in the tester. Then I was suppose to pump the bulb on top for a minute and see if it changed color. Well it was so hot it was making the plastic tube weak and I couldn't hold it on there long enough. So the fluid never changed color but each time I took the tester back off antifreeze would spew back out the neck because of the pressure that had built up.

So something is pressurizing the radiator. I am not sure why but I "THINK" it is a blown head gasket or a cracked valve seat??? So would the people with more knowledge than me weigh in here and offer up some ideas please?

Thanks Rick
PS: Any want a heavily modded Jeep??????????? I am pulling my hair out.

 

headgasket or cracked head allowing compression to leak into the water jacket.
do a compression test to identify which cylinders are low.