Air Bubbles or Aftermarket Stat Problem?

[Buffman]

I noticed while driving the wagon today, that after it gets up to temp (1/2 mark), the needle will eventually climb to maybe the 5/8 mark or somewhere in that area. No where neat the H and danger area but it goes above 1/2 Mark. I could have sworn I got the coolant bleed properly with that screw. I've been reading a few posts and some indicate that OEM stats are the only way to go. If I dirve 70mph or faster it will stay at half mark all the time.

The coolant system has been opened various times to change out radiator and such. The one I removed from car (did not look original) opened at the same time as the duralast one I put in (stove top test).

So is it possible I still have air bubbles in the system or should I really buy an OEM radiator cap and stat?

[94SS_Canada]

try OEM its not that expensive. From my experiance that sounds like a rad.

[Buffman]

radiator is brand new and system was clean and flushed before install. Funny thing is I'll let it sit in the driveway and it will stay at half mark all day long. HMM

[kimokalihi]

Yeah thermostats are rarely ever a problem with overheating. Does your heater work? Are you radiator fins all straight?

[Legacy777]

If you have an aftermarket t-stat, that's your problem. Replace it with an OEM t-stat.

[Buffman]

Yeah thermostats are rarely ever a problem with overheating. Does your heater work? Are you radiator fins all straight?

Yeah Heater works f*in great.. As I said radiator is brand new. It's not even overheating, as I described temp needle is just fluctuating more than what I'm used to seeing. I'll have to pickup a stock T-stat this week and get it in.

[evolutionmovement]

Yes, it doesn't matter if they work in hot water, they don't work in the cars. I'm not sure why, but you can certainly see the difference in appearance between the two. The OEM should be less than $20. I think I paid $12 last time.

[Buffman]

I noticed today the radiator cap doesn't seem to be allowing coolant in and out of the overflow tank. I marked it when it was dead cold last night and after driving it still is in the same spot. I have the stock one lying around, I'm going to put that back on too, and get a oem T-stat this week.

[kimokalihi]

Interesting. I'm pretty sure when I had my N/A 90 legacy AWD 4EAT wagon it never went above 1/3 on the gauge. Not once. Had it for 2.5 years.

[Buffman]

when i first got the car it was pretty much at half mark the entire time I drove it home. It hasn't been until I installed new t-stat that I've had the problems.

Can't find the darn oem radiator cap. Guess I'll have to get one of those too.

[ericem]

When I replaced my rad I made sure EVERYTHING was oem. Rad cap, hoses, thermostat. The biggest items that need to be oem is the rad cap and thermostat. The oem thermostat is plenty different. You can't even push open the stock thermostat by hand when cold. With aftermarket it is pretty easy.

[Legacy777]

Do the t-stat before you even try to look at any other component.

[93forestpearl]

OEM thermostat on the left, NAPA on the right.





Also, take what the factory temp gauge says with a grain of salt. I've seen 240° on my aftermarket gauge and the factory gauge wasn't even 3/4.

[Buffman]

I'm not too keen on trusting the stock dash temp gauge, but it does fluctuate. As to what temp 1/2 mark represents not sure without installing aftermarket gauge or monitoring temps with my temp gun.

Had to drive the subie to work today as it's getting too cold for the RMS (SPTs dont like under 45*F). I noticed at idle if will stay at 1/2 mark all day long. However any driving under 2800-3000rpm, temp needle will rise above 1/2 mark. If you're going above 3000rpm temp is at 1/2 mark. If you lay into it enough to go overe that rpm range temp guage will immediately fall. So to me that spells restricted flow somewhere.

Coolant I drained out of the car was really clean, and I found no sludge in the system or anything nasty. Waterpump looks to be replaced (unless OEM uses a extra silicone on things ) So in that case, the restriction to me would be the T-stat, and I will be replacing it Wed when I have time in the morning. Will keep you updated.

[PhyrraM]

Dash temp gauges are engineered with a 'dead zone'. Average everyday drivers (customers) tend to freak out if they see the gauge moving around. So the OEMs tend to have thier gauges get to "normal" fast (180 or so) and then sit in almost the same spot for as much as 40 degrees before they start moving again.

[evolutionmovement]

Yeah, OEM water pumps don't have any silicone.

[Buffman]

got the picture to come up. Yikes I've never seen a difference like that between an OEM T-stat and a aftermarket unit. Got the new OEM unit in my hands, and it's a beast. I thought this part # included a gasket but apparently not so hopefully the parts store gasket will fit it.

one that was in the car originally was definately not OEM either.

[Buffman]

Solved. The new radiator cap made it run cool a little better but it was still climbing. Today had time to put OEM T-stat in. I managed to get one of the block drain plugs out (impact gun on small one gallon compressor = nO POWER) and as I figured coolant that came out was nice and clean, no grit/sand/sludge/etc.


Put New OEM T-stat in. Got the system bled. Drove it all the way to work today, and it stayed slightly under 1/2 mark no matter what rpm range I was driving in. No Fans Constantly running either.

So I guess OEM or go home for the T-stat