Thermostats going bad 2 in 7 months?

[PGG]

I have had two AC delco brand new thermostats go bad in 7 months is there a problem in warm weather just leaving the damn thing out?
Is there a thermostat that is made worth a **** anymore?
I also had a brand new mechanical fuel pump go bad a 500 miles
I guess everything is made in china now or something.

Thanks for any suggestions. PG

[SavageC20]

I have had good luck with Stant Superstats. They're like $7 on Amazon and still made in USA. I bought a Carter fuel pump for my 454 and it hasn't failed yet I think it was $14.

[special-K]

I use Stant as well. It's what they do. But could it be something about your coolant causing it to stick?

I always use AC or one from a carburetor company like Holley or Carter

[CastIron]

You didn't say if they failed by not opening or opening too soon. I'm guessing they stuck closed? I'd say it unusual to have that happen, but maybe they had a bad batch.
I use Stant thermostats and haven't had any problems. And a Carter mechanical fuel pump that I installed a few years ago with no problems.

[KQQL IT]

I put a aluminum high volume water pump on my sb400 and it would hold the the t-stat closed. Put the standard pump back and the problems stopped.

[Chris_oz]

Stant here also, never an issue.

Be sure they are installed the correct way, I have seen several put in "up side down" which delays the opening and makes them close too fast.

I also loke to add a 5/32" hole to help bleed when filling the radiator, gets the air out of the block so much faster with compomising how the thermostat works.

[lok-dawg]

Had some issues with new thermostats too. I believe Murray is the brand. One was bad right out of the box and just simply would not open and engine would overheat immediately. Next one would take too long to open at times, it's become less finicky over time. I think I'd like to replace it though. Probably with a Stant based on the replies here.

[toolboxchev]

Stant recommends replacement of thermostat with Coolant Flush. I would do the radiator cap also.

Here is some info for my truck from their site. I am using the SuperStant Series. I am also using a 16lb Rad Cap to help with cooling.


https://partcat.com/stant

[tdangle]

I am also having issues with thermostats. You can actually see the temp gauge swing hot and then cool off within less than a minute. Last one I bought was a hi-po one (cant remember the manufacturer -- maybe mr gasket?) and it worked well for a month or 2 then started acting flaky too.

[rpmerf]

I would be looking at the rest of the system to be 100% sure it's the thermostat. Make sure the system is fully bled and 100% sealed. I've seen a pinhole leak cause a some weird issues before.

I also drill a bleed hole in the thermostat. Usually like 1/8". Some thermostats have a hole and check valve.

The high flow water pump is interesting. Makes sense.

You can test a thermostat in a pot of water with a meat thermometer. Heat up the water on the stove and see at what temperature the thermostat opens.

Verify temperatures with an infrared thermometer (temperature gun). My temperature gauge gets thrown off by my headers right next to the sender (or maybe my 195* thermostat). If I measure from the front of the head, intake manifold, block, upper hose, radiator, lower hose, it all looks good.

[tdangle]

Originally Posted by rpmerf

I would be looking at the rest of the system to be 100% sure it's the thermostat. Make sure the system is fully bled and 100% sealed. I've seen a pinhole leak cause a some weird issues before.

I also drill a bleed hole in the thermostat. Usually like 1/8". Some thermostats have a hole and check valve.

The high flow water pump is interesting. Makes sense.

You can test a thermostat in a pot of water with a meat thermometer. Heat up the water on the stove and see at what temperature the thermostat opens.

Verify temperatures with an infrared thermometer (temperature gun). My temperature gauge gets thrown off by my headers right next to the sender (or maybe my 195* thermostat). If I measure from the front of the head, intake manifold, block, upper hose, radiator, lower hose, it all looks good.

Not sure about the original poster, but I know I've run into issues I can't explain. My cooling system is in good shape, new water pump, very low mileage radiator all new hoses and no leaks. I have a closed system with an overflow reservoir new gauge sending unit and thermostat. 7 blade fan with HD clutch. 180 degree thermostat. I can be driving at a steady speed (or even stopped at a light) and watch the gauge move upward towards the upper range of the "normal" area and then just as fast go down to the bottom portion of the normal area. I have checked the true temp with a temp gun and it all seems to be in range. Almost as if the thermostat is hanging up opening and then fully opens, engine cools down right away and then maybe later does the same thing, but not always.

[MySons68C20]

Same as tdangle above.....brand new everything and the stock gauge goes to the edge of the hot range then back to the middle. It runs great no boilovers etc. I'm thinking the factory gauge may be very sensitive to a 5 or 10 degree temp swing.
I do have a new aluminum radiator with the big tubes....one thing I notice when I shut the engine off the radiator continues to make a gurgling noise.
I believe it is probably normal but not really sure.

[rpmerf]

I had a Dodge Spirit that would fluctuate the temperature gauge. I had a pinhole leak in one of the hoses. Not sure how, but fixing that pinhole leak stopped the fluctuation.

My Integra does the gurgle after shutdown. I know that car has a leak. I have to top it off and I can see dried coolant spray. Pressure drops pretty quickly after shutdown. I should probably fix it, but that car is beater status with 360K miles, so I just top off the coolant every month.

Makes me wonder if my 1/8" bleed hole is hiding a swing that I would have without it.

Really, as long as it isn't loosing coolant, can build and maintain pressure, isn't overheating or boiling over, I'd call it good enough.