Temperature Variations 160-195

[Greg]

What's the recommended pressure for a new cap?

 

[jcro61]

I believe 16, but when you go to the parts store they can look up the cap you need by application.

 

[GMCTRUCKS]

I seen at this auto parts store over here it's this chemical to where you place it by the tail pipe and it will let you know if you have a bad head gasket I didn't know that they still sold the stuff. Bad cap or a plugged up radiator or bad fan clutch. Let us know what you find?

 

[barebones 1500]

the cap sound like it could be that. try the cap and if that does not work then try a coolant flush. they sell a flush kit by Prestone, it comes with a coulpe of tee's and a nozzle for the radiator. all you do is tie the tee's into a couple of the lines and put the nozzle on the radiator, then hook up a hose to one of the tee's and blow it all out the top of the radiator into a bucket. kinda fun, but i would recommend draining the coolant before so that if you miss the bucket there won't a whole lot of coolant getting on the ground.

 

[Swaggerwagon]

You most likely have air pockets in the cooling system, probably in the engine block, near the temp sender...mine did the same crap after i changed my t-stat, i tried a new cap also, didnt fix the issue...

try this procedure...you need access to a steep incline, so you can point the nose of the truck upwards...like park it in a ditch line if available.

This needs to be done when the truck is completely cooled off...like in the morning.

park it on steep incline, nose of truck in air...have jug of coolant ready to pour in..

remove rad cap...

start truck...(its good to have a helper to run the engine at about 2000-2500 rpm during this procedure)

keep an eye on the coolant level in radiator, continually adding coolant as the truck "burps" out the air pocket/s in the system, you should see them bubbling out of the radiator as the truck is warming up....

at some point, the truck will stops burping out the air pockets and start pushing a continuous flow of coolant out of the rad....this method of removing the air out of the system will waste some coolant, so don't freak out when it pushes coolant out of the radiator, it's part of the process of getting the air pocket/s out of the system...

good luck...

 

[71 cuda man]

Are you sure the gauge &/or sending unit is working properly?

 

[fireball 440]

Mine does the same thing after replacing the T stat. The guage goes up to 210 then drops way down, over and over. Engine speed has no effect, fan clutch is working, no air bubbles coming out, heater blows hot air. I was gonna pick up a new cap but other than that WTF?

 

[Greg]

I'm going to try the cap today, if that doesn't fix the problem I won't be able to do anything until Xmas, and that is after a 6 hour drive. Will I be ok to drive 6 hours with varying temperatures?

 

[MikeRWK]

I agree with these guys first thing to check is the rad cap, i had a sunfire (never again!) that had a bad cap and wasnt letting the tstat open so it was overheating all the time.

 

[barebones 1500]

it is hard to tell, it could be just small bubbles or a bad sender and in that case i don't think it would be a problem but at the same time it could cause parts of the motor to rapidly heat up then cool down causing cracks. i think you should try a a cap then a flush before taking any long trips. but if you can't, then i would recomend getting a different car for the trip.