DI ovrheat with AC on

[BaldEagle]

well the radiator was flow tested, not simply looked at from the outside. i'm going to check for exhaust gasses this weekend but i really dont have any symptoms of a head gasket problem. i compared what i thought was high pressure in the system with my other disco and it was the same, so i guess i just never really noticed that before. its simply not getting enough air to cool down the coolant once the extra heat from the ac is added while sitting in traffic. it still sounds like a classic radiator problem, but it checked out fine with the flow test. i dunno. we'll just have see this weekend once i put the new water pump on and the boiled radiator. if i am leaking exhaust gasses into the coolant, then would simply turning off the ac nearly instantly rectify the temperature? wouldnt it overheat no matter what?

 

[jimjet]

Change the radiator

Id be very suprised if you changed it and came back cursing with the same problem as before.

Change the radiator.
and pump ,mine failed shortly after the rad and with your mileage if you havnt you should.

Jim

 

[jimjet]

Change the radiator.

 

[Steve Rupp]

These things don't need huge amounts of air flow to the radiator. I leave my ac blasting in the middle of the desert with 3 hella 4000's and a big winch in front of the radiator and it has never over heated. Change whatever you want but in the end I see a new rad going in.

 

[BaldEagle]

i completely agree, thats what i figured was wrong from the get go. it just threw me for a loop when he said it flow tested fine.
so it boils (no pun intended) down to this-
even if it flow tests out ok and is boiled over a brand new one will perform better? i appreciate everyones help

 

[Steve Rupp]

Here's what I'm saying.... I had the identical symptoms in my 94 with 140k back in 2003. I changed EVERYTHING because I was cheap and didn't want to blow my wad on the radiator. Well, the only thing left was the radiator and It was without a doubt the entire problem.

 

[robertf]

I installed Auto Meter temp gauges
The originals just dont work.
http://www.discoweb.org/forums/showthread.php?t=18613

Jim

Hey Jim what temps do you see on your gauges when driving? I'm trying to determine if mine is normal or not.

Its around 185 if its in the mid 80s, no AC. Mid 90's and AC it'll get up to around 200.

It does all this and the stock gauge stays right in the middle, sending units are right next to each other.

 

[88gspd]

BaldEagle, have you been able to determine the cause of your overheating problem?

 

[BaldEagle]

still working on it. i'll update once i get it figured out. i can say it was not the radiator or the tstat or the viscous drive though. head gasket checks out as well. i'll let you know

 

[ptschram]

Here's what I'm saying.... I had the identical symptoms in my 94 with 140k back in 2003. I changed EVERYTHING because I was cheap and didn't want to blow my wad on the radiator. Well, the only thing left was the radiator and It was without a doubt the entire problem.

LOL, I did the same thing and it wasn't long before I was learning how to do head jobs.:banghead:

 

[Darren M.]

At 118k miles, it is most likely a clogged radiator. Get it tested at a radiator shop and replace if found to have restricted flow.

You might also want to consider replacing your viscous clutch with a heavier duty one for a 1998 Chevy Blazer 4.3L w/ AC if you don't mind having your truck sound like a school bus.

I had to do the heavy duty clutch. Truck sounds like an F16 coming down the street, but no overheating with the AC on since the original problem came up last July.

 

[Steve Rupp]

LOL, I did the same thing and it wasn't long before I was learning how to do head jobs.:banghead:

The heads were in the back of my mind but it wasn't going through any coolant.

 

[88gspd]

still working on it. i'll update once i get it figured out. i can say it was not the radiator or the tstat or the viscous drive though. head gasket checks out as well. i'll let you know

This may help you diagnose the cause: http://www.robisonservice.com/articles/RonR_march2006.asp

 

[BaldEagle]

despite what i said earlier today it has to be the radiator even though it was flow tested. new tstat didnt help. waterpump was fine. coolant temp sensor is fine. viscous clutch was bad but a working one didnt help. it only does it on a really hot day (today) with the ac on. its just enough heat i guess. it sat in the driveway last night when it was cool outside and ran for a long time with out getting warmer than normal. but today at lunch and early evening while sitting it would try to get too hot until i turn off the ac. i just wish i could have some kind of confirmation that it is the radiator before i buy one, even though all signs point that way.

 

[agbuckle98]

Get it re-cored. My rad shop takes out the original 3 row core, and replaces it all with a 4 row setup. Costs about 100 bucks less than a new aftermarket radiator, and I think you end up with a better end result.

 

[BaldEagle]

good idea. i'll call a few rad places and ask about that

 

[sven]

I tried going down the re-core route. Unfortunately every shop wanted 450+ around here. A new 4-core rad from RN is like $320.

 

[ptschram]

I tried going down the re-core route. Unfortunately every shop wanted 450+ around here. A new 4-core rad from RN is like $320.

Thank you. I've had the same experience, cheaper to buy new than recore. When recoring, the condition of the tanks has to be taken into account as well.

With respect to the three/four core debate, I just scrapped seven radiators and all of them were four core. When you rip the steel off to increase the scrap value, you get a very intimate view of a radiator.

 

[Darren M.]

"dont eliminate that.

Mine was boiled and flow tested on my 98 and it still overheated AGAIN.

Just buy a new radiator and do the pump while your in there and be done with it.

When i had my problem it was fine around town , on hills ect ect.
but on a long cruise to work it would slowly creep up to an uncomforatble temp."


X2:applause:

 

[BaldEagle]

i already put the new pump in. new radiator it will be.