replaced water pump and thermostat, now temp gauge is floating up and down...??

olyjeep · 05-12-2005, 08:19 PM

Tonight I just replaced the thermostat, and water pump (and radiator which is what blew on me in the 1st place). But when I got it all together, I started the car and at idle, the temp gauge went into the red.

My radiator hoses and tstat housing were not warm so I guess the tstat was not opening at the right temp at 1st. I shut the motor off. Let it sit, poured a little more water in the radiator. Started again, idled, and then I could feel the tstat opened up, coolant was flowing, and the temp came down.

I drove it for about 15 minutes and it does not overheat, but the temp gauge gets up to around 190-205, then falls back to 150-160-ish. It continually does this over and over. It never settles at one temp like it used to.

Bad thermostat? Bad temp sensor? I do need to have the system flushed out still and thought maybe I was a little low on coolant but I think it is all full now.

Any ideas on what this could be?
Thanks!

**rustywrangler** · 05-12-2005, 08:29 PM

Sounds like the same thing mine does. I dont know if it is a problem or not but its been working ever since. (4 years) just did head gasket and new water pump gasket and therm just cuz i had oil in the system from the head gasket and it still runs the same. up down up down.
just my 2 cents

olyjeep · 05-12-2005, 09:16 PM

I also forgot to mention that my old thermostat was cracked when I opened the housing up. I don't know how long it was like this or if it happened when I overheated last week.

It may have been stuck open? I never checked to see if the heat was hot (being that it's spring and all...I haven't used it lately)

Could I have screwed something up with the temp sensor when I overheated? Anything else I could check? I am probably going to at least throw in another tstat to see if maybe I just got a faulty one at Napa. I don't know what else could be causing this..??

jeepnguns · 05-12-2005, 10:55 PM

I would bet on a bad t-stat. it was stuck and now it is sticking.

JustPassinThru · 05-12-2005, 11:02 PM

Curious. I have the same thing...late last season I replaced the water pump and thermostat. Then nothing but short hops till winter storage.

Now, this spring, the temp needle is all over the place. Not into the danger zone - but between where it should be and far too cold. It's not hydrolock or air bubbles - I've put 1000 miles on the rig this spring so far.

I was betting on a bad sending unit; as with the oil gauge. Was planning to replace either the sending units or the gauges with mechanical. Now this...I don't know.

olyjeep · 05-13-2005, 08:51 AM

I'm going to throw a new tstat in this weekend if I have time and see if this takes care of it.

At 1st I got worried that I may have bought the wrong water pump after I read that there are 2 types. Regular and reverse flow (my old WP had the little R stamped on it but I forgot to check the new one b4 I put it in)

But I think if I had the wrong flow, I'd be overheated instantly right?

deuce · 05-13-2005, 10:01 AM

I know if your radiator has air in the system it will do the same thing, the temp will fluctuate.

olyjeep · 05-13-2005, 10:16 AM

Yeah I bet probably do have a few air pockes in there actually.

I just took it to a local shop to have it power flushed to get all the stop-leak (and other crud) that was in the system out. Once they fill it up, hopefully my floating temp problem will be gone.

farmboy1976 · 05-13-2005, 12:03 PM

Mine went to hell a long time ago, I went down to Motor Parts got a new sending unit, and gauge and mounted it below the stearing wheel. That was a lot easier and cheaper then trying to replace the stock one. If nothing else for $20 or less you can try a different gauge and sending unit to see what it is.

Just my $.02.
Good luck.

olyjeep · 05-13-2005, 02:52 PM

Well, I just got back from having it flushed and still bouncing... I guess next step is pop in another thermostat and go from there...

BudmanV6 · 05-13-2005, 11:15 PM

You don't need a new thermostat. This problem was discussed a while ago in August 2004 JP Magazine. Fist of all, make sure that the "thermostat's temperature-sensing pellet" faces the engine block. I believe that that is the spring. Regardless, they said that many thermostats have a small hole to keep a trickle of coolant flowing even when the thermostat is closed to keep the temperature more constant. If your thermostat doesn't have one of these you need to drill a 1/16 inch hole in the flange. If you want I can post a pic on here.

olyjeep · 05-14-2005, 09:29 PM

Yeah, I definately have the thermostat in the right way, spring facing the motor.

I also asked around about the weep hole in the thermostat (the one I put in does not have one), but everyone I asked said there is no weep hole on the tstat for the 95 2.5

I have a new thermostat I need to throw in this week to see if it helps. but for now, it's running great, just the temp gauge is still bouncing from 200 to 160 ish..over and over...

Ben_321 · 08-04-2009, 01:49 PM

sounds like you jsut have some air in the cooling system still and its moving around and throwing the t-stat off....or you got a bad thermostat....

kampoyj · 11-09-2009, 04:59 PM

Guys could you give me a step by step on how to burb the system properly? I recently changed rad and i dont believe i have burbed it right.I get the same with needle playing up on me a little bit above 200F and i suspect its air still in system

**rustywrangler** · 11-09-2009, 05:01 PM

Quote:

Originally Posted by kampoyj

Guys could you give me a step by step on how to burb the system properly? I recently changed rad and i dont believe i have burbed it right.I get the same with needle playing up on me a little bit above 200F and i suspect its air still in system

I answered in the previous thread you asked.