94 discovery overheat problem

[th22973]

My 94 disco has just started to overheat, But this only occurs when it goes up a mountain at highway speeds, Going down the mountain and on flat terrain, problem does not seem to exist? Any Suggestions? Water pump seems to be ok, Radiator is full, Thermostat seems to be working?

 

[garrett]

i would just replace the thermostat anyhow just in case that MIGHT be the issue. only takes 15 min and $10.
possible if everything seems to be working fine that you could have a radiator that has sediment in it. therefore it may look full but only running at a lower capacity. it has been know to happen.
you can always have a local shop pressurize your system to ensure there are no leaks and the fans are working properly.
does your viscous fan come on? how about the main fan after you turn the truck off?
there are also fan switches that tell the fan when to go on and off.

just start elimintating things starting with the easiest and least expensive.

 

[MUSKYMAN]

is your trans fluid low?

 

[th22973]

Transmission does not appear to be low, when warm the fluid looks to be over full, When cold it and running it is right on the mark


COuld it overheat if it was overfull??

 

[RoverChic]

Do you have a CEL on? I might also check the ECTS too. Are you losing coolant @ all? Try and smell the ****** fluid as well (should not smell burnt)..Should not be dark brown but more pinkish. Good Luck!

 

[Sergei]

Is it overheating (or looks like) when you going on high rpms in slow stop/go traffic?

 

[ShaunP]

Start with thermostat, and then look at the rad and viscous fan coupling. Also while it won't cause it to get hot till it popps anyone who has a Disco with a Black plastic rad header tank replace it before it splits in 1/2 and cooks our engine, replacements are white and made of different stuff cost about $120 Australian for the LR part.

 

[th22973]

The temp gauge does increase (But no where near the H)at high rpms and stop and go traffic (Randomly) But will go to H on the temperature gauge when going up a mountain, When going up a mountain, it does not seem to be function of RPM. Thanks for all the replies, I am just puzzled, I can run a 400 mile trek in one day with no problem, but when I cross the Shenadoah National park for about 3 miles, The gauge pops up to H or darn near close to it, When I descend the mountain and get on flat ground it goes back to normal and stays there

 

[fergy]

Continue to have a similar problem with my 97 D1. In preparation for a road/camping trip I thought I'd replace the original radiator hoses and coolant. Thinking that with 100K on the clock, it would be the wise thing to do. Never had I experienced an over heating problem with my D1 BEFORE. Well to make a long story short, I'm driving along to the final destination and look down at the gauge and I see it above the 1/2 way spot. Within 3 minutes its up to H. Pull over, let it cool and drive 1 more mile, bingo, its back up to H.
Well this goes on for the next 4 hrs. Finally make it to the camp site and unpack in the dark. The next morning I go out and turn the ignition on,.... temp immediately goes to H. Well at least I know its not the hoses or coolant. Make it home and replace every temp sensor and sending unit. For the rest of the month, truck run fine (normal reading). Then a few weeks ago in stop and go traffic, ITS BACK. Have yet to figure it out, I'm about out of ideas and thinking of taking it into the dealer.
Good luck in determining your over heating gremlin.
fergy

 

[Kris A]

I had a similar problem with my 98 at 65k. I found that if I blasted the heater it would help while going up hill. Dealership said the radiator was clogged so they rodded it. Has worked fine ever since. (Of course the clogged radiator wasn't coverd under the waranty where a leaky on would have been?)

I think trying the heater to see if it helps with cooling may point to the radiator.

-Kris

 

[peter]

new radiator, that is the only way you will fix the problem.

 

[davidz]

yepper Peter has it, your radiator has lost its its ability to disipate heat properly. replace or have it recored, wouldnt advise rodding a 10 year old radiator .

 

[scubaman99]

Hey Troy,

Most of the the guys on the norcaldisco llist with 94-97 DI have beat this discussion to death...

symptoms: running your rig on flat road or on hilly roads when your AT speed is no problem. Running on hilly roads at a very slow pace <25mph or running your rig up hills loaded down with lots of stuff... and your rig over heats.

cures:
1. Check all fluids (duh)
2. Replace thermostat... most likely a 94-97 DI is going to have substantial miles on it... thermostats are cheap and easy to replace... just do it. you might get lucky... (parts cost <$20)
3. Rod, recore or replace your radiator... this is most certianly one of the biggest problem spots. again, most 94-97 DI's have substantial miles on them and their radiators are almost certianly clogged to some extent. (parts cost <$300-$450 depending on which route you take = rodding, recoring or replacing)
4. If #3 doesnt solve your problem completely, replace your Viscous fan clutch. The fact that over heating mainly occurs while going slow is a sign that your radiator isnt exchanging heat effectively. If replacing your clogged radiator isnt enough then the next most logical part of the puzzle is that the viscous fan clutch isnt pulling enough cool air over the radiator. (Parts cost $175-$250 depending on source)

One of the norcaldisco guys has even found a local radiator shop that will recore the DI radiators with a 5 core center for even more efficient cooling. I think RadiatorLand charged something like $450 for a 5 core DI radiator.

good luck!!!!

KEN

 

[Surgeoh]

cures:
1. Check all fluids (duh)
2. Replace thermostat... most likely a 94-97 DI is going to have substantial miles on it... thermostats are cheap and easy to replace... just do it. you might get lucky... (parts cost <$20)
3. Rod, recore or replace your radiator... this is most certianly one of the biggest problem spots. again, most 94-97 DI's have substantial miles on them and their radiators are almost certianly clogged to some extent. (parts cost <$300-$450 depending on which route you take = rodding, recoring or replacing)
4. If #3 doesnt solve your problem completely, replace your Viscous fan clutch. The fact that over heating mainly occurs while going slow is a sign that your radiator isnt exchanging heat effectively. If replacing your clogged radiator isnt enough then the next most logical part of the puzzle is that the viscous fan clutch isnt pulling enough cool air over the radiator. (Parts cost $175-$250 depending on source)

5. Have the reservoir cap (radiator cap) pressure tested.
As you increase altitude, atmospheric pressure drops. Caps are rated at 15psi sea level. If the cap is'nt capable of holding the pressure the coolant will reach a higher temp. It's the easiest, cheapest, quickest thing to check. If you haven't flushed the block and radiator in the last 3 yrs, then do it. I mean really flush it out with a garden hose till clear water comes out of the other end of the radiator and both drain plugs in the block.
If you've never done items 1-4 do them now. It's better to do it now than on the side of the road when you're trying to get somewhere.

 

[Steve Rupp]

Cooling problems are a total pain in the ass to diagnose. In my 94 I was having some overheating problems. It would operate normally for a while then shoot up like crazy. After changing the t-stat, fan clutch, coolant, and hoses there was only one thing to replace. The radiator. Because the radiator is so much money, I really didnt want to do it. Being an electrician, I have a pretty awesome mulitmeter with all the cool attachments. I got the truck up to operating temperature. When I got it home, I took the infrared thermometer and started checking the radiator inch by inch. I noticed that the bottom half the radiator had a considerable temperature difference than the top half. At this point I decided to just order a new one. I bought from Nathen, who was about $100 cheaper than everybody else. I threw the new radiator in and my problem was solved. Point is, Don't just start replacing parts in order to diagnose a problem unless you're made of money because it'll get pretty expensive. Do it right, think about it and try to narrow it down.

 

[Colin Campbell]

Curious

I'm curious what eventually was was the cause of your overheating? My 96 D1 is doing the same thing overheating on hills. Thanks