1990 Chevy S-10 Over heating

PITTBULL_032000

MEMBER
1990 CHEVROLET S-10
6 CYL
4WD
MANUAL
160,000 MILES

My truck started to over heat a few days ago. I replaced the water pump on because it was leaking from the weap hole plus it sounded like it was about to go out before long. It is still over heating! It starts off running normal temp but after awile it hits 210 then it slowly makes its way up to 260 and sometimes it will drop a little a then go right back up. I put another thermostat in it still nothing. I thought maybe the coolant sending unit was bad so I replaced it an no luck. It got so hot on me today it blew steam and I thought it was on fire! I let it cool down then I took the thermestat out thinking that it would run colder and get me home but It still went to 260. Over the summer I put a new heater core in it and I have heat so I know its not bad. I'm not losing any coolant or anything. I would greatly appreciate it if anyone could help me. Thanks!

3 Replies

JACOBANDNICKOLAS

MECHANIC
108,262 POSTS

If it is overheating with the thermostat out, then the radiator has to be plugged. You've replaced everything else.

What I recommend is either flushing the cooling system or having the radiator "rodded out". If the problem still continues, then you need to check for a headgasket problem.

Let me know what you find or if you have other questions.

Joe

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Thursday, November 12th, 2009 AT 7:59 AM

PITTBULL_032000

MEMBER
3 POSTS

I know my head gaskets are good. I haven't seen any signs of them being the problem. I'm in the process of putting an Intake Gasket on my truck. I found a small leak coming from the front of the Intake where the rtv sealant is on the outside so I just went ahead bought the stuff to replace it. I don't think thats the problem though. I think it may be in the Radiator. It doesn't over heat with the thermostat out. I just put new antifreeze in it and it was green. I went to check it the other day it was redish brown so I drained it and bought a bottle of Prestone flush. That didn't help so I think I either need a new Radiator or need to have it professionally cleaned.

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Thursday, November 12th, 2009 AT 11:04 AM

RISABEAN

MEMBER
1 POST

I myself have a 1990 s10 and I had a coolent leak comeing from my water pump gaskets so I figured why replace the gaskets and not the water pump since I was going to be down there anyways. So thats what I did it, made sense to me even though it wasnt over heating pryor, I also changed the thrmostat and when I started it up I had a excessive overheating problem for a few days I scambled to try and find the problem i.E. Rediator, temp sensor, cloged water ways ect. Becouse the water pump I bought was new not reconditioned. Well to make a long storie short I had to go back to square one it was the water pump it was bult wrong and pushing water in revirse and that was confirrmed by the parts house I bought it from when I took it back becouse they were curous also so they took it apart and found that was the reason for malfunctioning. I took the time to write this becouse I was doing research when I was going threw all of this and found this post so I thought I would share my experience and let you know that sometimes the culprit can be the new parts them selfs and please remember just becouse a part is new dose not mean its good, just some food for thought hope everything gose well and good luck!

P.S. I had my problem 2 days after your post so who knows maybe there is a bad batch of s10 water pumps going around its something to look into?

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Friday, November 13th, 2009 AT 8:59 PM