cant figure out overheating problems

tford35 · #1 04-06-2006, 09:20 AM

I have a 97 passport 4wd that keeps overheating. The radiator was flushed out a week ago then the thermostat replaced, then the fan clutch was replaced. I put a shop rag in front of the radiator and it sucked it in, so that works. The water pump was cycling when we were replacing everything, but it overheated this morning on my way to work (a 10 mile drive--no stop and go traffic). Any solutions to what may be the cause now? What should I look for if it is the water pump, a cracked head, or a bad radiator? Thanks for your help in advance!!

Ramblin Fever · #2 04-06-2006, 09:51 AM

Just went through some cooling system issues myself - in regards to a radiator flush with the installation of new hoses and a thermostat. 2 days later, we found one of the clamps not tightened down on the lower radiator hose - didn't overheat, but was peeing a lot of green juice.

A week later my waterpump went out, had 90k miles on it, and it didn't give but a half days warning - had it towed to town where they fixed her up, this whole time the truck did not overheat, although the radiator was sucking in antifreeze from the reserve, leaving the reserve dry, but the radiator was always full.

I wonder if it didn't overheat because Colorado was in an artic freeze that whole week.

Couple of things - it is always possible to end up with a bad thermostat, stuck in the closed position; another thing is clamps can prove to be weak even when they're new.

Are you dripping antifreeze anywhere?

tford35 · #3 04-06-2006, 10:01 AM

ok, sounds like the trouble I am having. I am losing antifreeze in the reserve like you did, but show no leaks anywhere also. That has been going on for a few months. I will check the clamps later today also before I do anything else. Is there a way to find out if it IS the water pump, or just replace and pray?

amigo-2k · #4 04-06-2006, 12:58 PM

http://isuzufaq.ibctech.ca/#faq75

Quote:

"anyway my V6 rodeo keeps boiling over and/or runs hot. there is no coolant leaking at all and I flushed the radiator and removed the thermostat. the coolant was nice and green when I drained the radiator and it flushed nicely. it looks as though there is coolant flow when i take off the cap. does this water pump have a weep hole that indicates a failure? as I said, no leakage. I was thinking that maybe the flow i saw was just hot water expanding and displacing cooler water??
seems like a ghost in the machine. all mechanics out here are criminals, so I'd like to fix 'er myself. any thoughts? any tips on pulling off that water pump?...it looks tricky.

so after flushing out the entire cooling system and putting in a new t-stat I'm still having this same issue...the engine temp gets hot when at idle or at a stoplight and yet the heat turns ice cold till the truck gets moving again

I had this problem with my '96 Passport - it would run cool most of the time, but then if I went up a hill, or ran on the highway it would overheat. If yours does this then the problem is capacity - that means your radiator is clogged, probably by hard deposits that can't be flushed. I tried flushing mine in both directions with heavy duty flush and it didn't do a thing. I replaced the water pump, thermostat, fan clutch, and all hoses. Still overheated. Then I replaced the radiator, and that solved the problem. At least now everything is new... "

surferfletch · #5 04-06-2006, 03:42 PM

If you're losing antifreeze, you've got a leak and a pressure problem. You'll overheat. Track it down. Look on the top of the block, under the intake. Look way down in there. Look at the front of the engine. The pump is buried under the timing belt covers, so you won't see fluid coming directly from the water pump. Look under the truck, between the tranny housing and block, where leaking freeze plugs would show.

Is it the original water pump? How many miles on the truck?

If it's not a leak, then you could have the stuck tstat, bad water pump, or clogged rad. Flow was good when you flushed the radiator?

tford35 · #6 04-06-2006, 04:35 PM

Thanks for the quick link--will let you know after this weekend what solved the problem.

Canucklehead · #7 04-06-2006, 05:07 PM

Quote:

Originally Posted by tford35

Thanks for the quick link--will let you know after this weekend what solved the problem.

After all that you have done, I would change the radiator cap as well. They're cheap and everyone seems to forget about them when a vehicle overheats.

HI JOHN · #8 09-25-2006, 05:28 PM

I replaced the atifreeze and begun to overheat. I thought the fan clutch was out or the fan clutch. I didn't realized that I had to re-check the coolant level once it cool down to fill it again. When you do a coolant change it will only take 1/2 of coolant and will make you belive that the radiador is full. You have to run the car untill the termostat opens so coolant can run through all the engine and then fill it up again.

2eyefishclaw · #9 09-26-2006, 10:57 PM

try to find someone to pressure test the sys to see if you can find a leak that way

surferfletch · #10 09-27-2006, 06:34 PM

Quote:

Originally Posted by 2eyefishclaw

try to find someone to pressure test the sys to see if you can find a leak that way

Good advice there. I tried to track down a leak which a pressure test showed was coming from a freeze plug between the block and tranny. Would have saved me several hours of looking.

Sorry to the regulars who have heard that story ad nauseum!

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