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Hi,I’m going to be replacing the thermostat in my car this weekend (1990 305 TBI) since it’s periodically sticking closed. Would I see any benefits from running a 180 degree thermostat or should I stick with the factory 195 operating temp. The car is all stock. Thanks in advance for any input from those who have experimented with this.
Thanks for the input guys. I live in California so it gets over 100 easy in the summer. Sometimes it can be 90 in December.lol. It can also get down into the 30’s at night at times. I wasn’t sure how much 180 would affect the heater performance.
Last edited by JimRockford; 11-09-2020 at 09:42 PM.
When stock type thermostats fail, they stick CLOSED, causing your engine to overheat.
Whatever temperature you decide to use, I suggest you get the high-flow type that if it should fail, it does so in the OPEN position. All that happens then is you don't get heat. No overheating.
Look for Stewart, Mr Gasket, Milodon, RobertShaw.
Here is an example: https://www.jegs.com/i/Milodon/697/16401/10002/-1
I run the Stewart high flow 160 without issue. The cooling system on these cars sucks anyway so give it every advantage is my theory. Mine still runs between 190 and 200 in the current 50-60 degree weather.
I run the 180 and have not had issues with low heater output and car runs great. When I had a new prom done I had the tuner lower the temp that the fan comes on, made a nice difference in running temps.
I run the Stewart high flow 160 without issue. The cooling system on these cars sucks anyway so give it every advantage is my theory. Mine still runs between 190 and 200 in the current 50-60 degree weather.
GD
I had a 160, never again.
I'd probably do a 180 though.
Reasons: During the colder spring/fall days, a 160 on the highway just doesn't make enough heat for the cabin.
I have a 195 in there now and at highways speeds the thermostat is almost always closed or cycling just enough coolant to hit the hysteresis.
On 50-60* days a 160 will drop the engine to 160.
If I were road racing the car constantly I'd probably run a 160 as the engine would be making loads of heat and I'd want to be able to shed it through the cooling system as fast as possible if needed.
Last edited by Thirdgen89GTA; 10-31-2020 at 10:42 PM.
Here’s where my temp gauge sits now when the car is warmed up and moving after the 180 degree thermostat installation. The malfunctioning one I removed was the stock 195 temp unit. With that one it read a little above the second line when at speed with air flowing over the radiator.
Is the line between 100 and 220 supposed to be the 200 mark? Because after 220 it would seem to be 240 and then 260.
Last edited by JimRockford; 11-09-2020 at 10:45 PM.
When I replaced the thermostat took care to clean the remnants of the old gasket off the housing and intake. The gasket I got was a paper/fiber type. One side had a peel off adhesive side. The other didn’t. I put some permatex water pump/thermostat housing rtv gasket maker on both sides and the thing is still weeping/leaking slightly. Is the correct gasket rubber?
Thanks! It looks like these actually have a rubber o ring molded into the gasket! The one the parts store gave me didn’t!
do these require any permatex,or do I just install them dry? For some reason when I enter my vehicle info it says it doesn’t fit it.
would this one work https://www.autozone.com/gaskets/the...0_1545803_6943
You haven't told us what car/engine you are working on, but if it is a SBC this is the correct one as @NoEmissions84TA linked
sorry,1990 Camaro rs,in the first post I had stated the engine info 305 tbi. The one I got from Napa https://www.napaonline.com/en/search...=nol-veh-conds was just plain paper and had a peel away adhesive back on one side. I was told I didn’t need to use permatex. First one leaked. Bought another and replaced and used permatex and it’s still weeping.
Autozone shows these fitting my vehicle. Of course the AC delco replacement isn’t available. It appears to be paper with a rubber ring molded into it. The felpro is rather pricey $14 for a gasket. Does that type need permatex?
I'd put a little gasket sealer around the bolt holes but not on the rubber.
the thin paper ones are prone to leakage when the mating surfaces are not pristine. with time you'll get some pitting and corrosion on the aluminum mating surface of the t-stat housing or intake fitting. that fel-pro gasket should fix it.
When I replaced mine last spring I used the Fel-Pro without anything on the thermostat housing and it hasn't leaked a drop but I did clean the mating surface before ensuring it was smooth. I picked mine up from Rockauto and it was 0.89 cents part#35062 and i believe that will work on your car as well.
I hate those paper gaskets, I tried using the ones supplied with my AC Delco water pump and they leaked immediately, once I put the good Fel-Pro gaskets on it was fine. I used Permatex water pump sealant on the pump gaskets both times, the thicker gaskets just work better and don't tear easily IMO.
I missed the engine info, I even went an looked again, I guess my CRS is getting bad. You install the paper gasket dry, that might be why it is leaking. You should also use sealant on the bolt holes for the water outlet, sometimes they are drilled into the water passage.
The FelPro is a PermaDry gasket, it is a hard plastic piece with an O ring bonded/molded on either side. I had a BBC that would weep because the intake manifold wasn't completely flat and had some gouges in it. I used the FelPro and it solved that problem. Now it is my go-to since it is reusable
I missed the engine info, I even went an looked again, I guess my CRS is getting bad. You install the paper gasket dry, that might be why it is leaking. You should also use sealant on the bolt holes for the water outlet, sometimes they are drilled into the water passage.
The FelPro is a PermaDry gasket, it is a hard plastic piece with an O ring bonded/molded on either side. I had a BBC that would weep because the intake manifold wasn't completely flat and had some gouges in it. I used the FelPro and it solved that problem. Now it is my go-to since it is reusable
No worries. The first paper gasket I bought when I installed the new thermostat I did install dry (without any sealant) it had a peel off adhesive on the back on one side. It leaked a little so I bought another one and replaced it and discovered it too was weeping/leaking yesterday and I used the permatex water pump/thermostat housing rtv that time.i put it on both sides all around the gasket including the area around the bolt hole.
I guess I have to break down and spent the $14 for the felpro perma dry gasket then?
I guess I have to break down and spent the $14 for the felpro perma dry gasket then?
You can do that, or buy a fine tooth file and try to carefully flatten the bottom of the water outlet and the intake manifold. Or if you get a small flat piece of metal and some sand paper to try to block it flat.
Also, don't forget that the screw holes may be into the water passage and could be your leak point?
Dont waste any more time on the gaskets. Engines and mating surfaces go through changes with age and end up with warping/pitting. Ditch the gasket and put a bead of RTV (about thickness of a gasket) all over one mating surface. Install immediately. Wipe off any excess that squeezed out (should be just a little if you used enough RTV) and allow to dry overnight. Presto, no more leaks ever. You might get a paper gasket to seal initially, but paper and cork dry out quickly and are likely to leak eventually. RTV lasts forever.
Thanks for all the advice. On my way to work I stopped by the Chevy dealership and got a gasket from them for $2.50 that has what appears to be a thin rubber ring on each side. Should I use permatex sealant on this type or just install it dry?
Last edited by JimRockford; 11-10-2020 at 10:23 AM.
The Felpro is what I used with no problems. Also, make sure (as others have said) to apply thread sealer (not RTV!) to the bolts.
Ok,I didn’t put thread sealer on the bolts themselves. What specific product do you recommend? When I had removed the bolts they were dry. I didn’t see any sealer on them
I've never had any problem with that Fel-Pro gasket dry ( The 35562T). Best thing I did was smooth the surface of the housing with fine W/D sandpaper on a solid flat surface to take out any rot or slight warping that may have occurred since it's aluminum and thoroughly cleaned both surfaces. This is after first leveling it off with a fine cut file as mentioned above. Never leaks a drop
I always figured since 220 minus 100= 120, then half would put the line at 160. My car stays generally between that line and the 220 mark, making the temp at 180-200. Seems about right or close enough?
I've never had any problem with that Fel-Pro gasket dry ( The 35562T). Best thing I did was smooth the surface of the housing with fine W/D sandpaper on a solid flat surface to take out any rot or slight warping that may have occurred since it's aluminum and thoroughly cleaned both surfaces. This is after first leveling it off with a fine cut file as mentioned above. Never leaks a drop
I always figured since 220 minus 100= 120, then half would put the line at 160. My car stays generally between that line and the 220 mark, making the temp at 180-200. Seems about right or close enough?
i was guessing it was the 180-200 mark but it doesn’t follow the same 20 degree increment the other side of the scale does. I guess the only way to solve the mystery would be to use one of those infrared temp sensors and see
I used a cheap $5 Autozone paper gasket on mine with no RTV and haven't leaked any coolant. I did lay some fine sandpaper down on a piece of granite countertop and resurfaced the aluminum coolant nozzle before install.
I installed the gasket I picked up at the Chevy dealership this morning. Worked great and no leaks. The previous gasket I had purchased from Napa. Not sure who made it but it had a peel off section on one side with adhesive. When I removed the thermostat housing this evening the clear film adhesive just lifted off in a sheet like cellophane. It appeared to have separated from the gasket material and the coolant was weeping between it and the gasket. Thanks to all for the advice and sharing your experiences.
I would just like to report, with much frustration, that the Fel-Pro 35562T does NOT fit on an 88 305 TPI despite what all the "fitment" guides claim.
This was the last thing I was going to do before putting the intake back together, and I have been stopped short once more due to believing this gasket would fit.
I guess I am stuck with the paper gasket then, which I will have to get tomorrow.
I would just like to report, with much frustration, that the Fel-Pro 35562T does NOT fit on an 88 305 TPI despite what all the "fitment" guides claim.
This was the last thing I was going to do before putting the intake back together, and I have been stopped short once more due to believing this gasket would fit.
I guess I am stuck with the paper gasket then, which I will have to get tomorrow.
Why does it not fit? I installed this on my 88 TPI and on my 92 TPI without any issues. Works perfect since 2019...
Oh yeah, that black on looks like the right shape, but can't tell on size. That Cometic looks like a nice design.
The black one may be for a V6 car? IIRC it's a little smaller for the 2.8/3.1?
The black one has the part number for a V8. I don't know what happened. But when I bought the axle seals for my rear, they shipped me the wrong seal in the right packaging.
Perhaps that happened here.
Either way, the Cometic seems nice and durable. Ran me about $20, it's also reusable so if I need to replace my thermostat again down the line, that should be a little simpler.
180 for me. They had 195 T-stats in them for emissions not optimal performance. I live in MN, my heat works fine.
Absolutely! 192-195* F T Stats were created for EMISSION reasons ONLY! 180 is FINE for heat and will put your engine management in "Closed Loop" quickly.
10-31-2020, 01:35 PM
