Hey all.

91 Firebird 5-speed. Swapped a 92 Camaro TBI in because the original engine had a rod knock.

Anyway, the previous owner said the original engine had overheated (didn't say why or how many times).

So, I swapped in the 2 Camaro engine and guess what. It still overheats. More specifically, the first time, it was sitting there at idle in my back yard and steam started coming out of the overflow reservoir. Ok, so I replaced the temperature switch (which had corroded and broken apart when I removed the original from the DONOR engine. I had a hard time finding the part so I put a brass plug in the hole, thinking it wouldn't make a difference.

Yeah... so no I have the new temp switch in, all wired up and I'm thinking ok problem solved. So I'm out there trying to isolate a small oil leak, engine idling, and POP! The radiator cap shot off and antifreeze SPEWED everywhere!

WTF! Top and bottom rad hoses are both hot but the rad fan doesn't seem to be turning on. Is this the reason for Old Faithful coming out of the radiator or the overflow tank?

Thanks in advance for any and all replies.

 

First thing I would do, is a block test. Make sure you don't have a blown head gasket pumping exaust gas into the cooling system.Then check your fuses. Also make sure the cooling fan works by sending direct current to the fan motor. If it kicks on, then check the cooling fan relay to make sure it is working correctly. The fan should kick on around 220F or just slightly past that. (asuming this is a V8)

 

The head gaskets are good. I'm sure of that.

I don't know what a block test is. I'm sure I can figure it out.

I had hoped to avoid any electronic work here because car wiring is NOT my strong point, although I can read an electrical schematic better than I can read a book .

If it stops snowing out at a reasonable hour today, I'll go fire it up and take a look.

Otherwise, I appreciate the reply!

 

How old is the cap?

 

LOL it's probably the original cap.

I have since "bypassed" the problem, however. I wired a manual ground switch in place of the temperature switch that goes in the passenger side head. When I see the temp gauge rise above 220 - 230, I flip the switch and the temp gauge stays around 180.

The issue is, that was a BRAND NEW temperature switch, and since grounding the wire that goes the switch works, that means the wiring is good. So how does a brand new switch fail like that???

Anyway, I'm wondering if the 3 wraps of pipe seal tape I put around the switch, before installing it into the head, is preventing continuity to ground...

Also, I've tried the A/C control, and that turns the fan on as well, so the fan and the wiring associated with it is definitely good.

 

You could get a multimeter and do a continuity test between an engine ground and the metal body of the switch. Do it for basically any sensor you screw in like the knock sensor too.

You dont need tape, I've always used a super small amount of sealer and never had it leak.

You could also leave your fan going. Your thermostat will keep it from cooling the engine down too much, and leaving it on is insurance against forgetting to switch it when the temp gets high. My fan has no thermo control, the car didnt come with an electric, it was added by a previous owner with just a manual switch. Forgetting to turn it on once was enough. Luckily it was just a pinhole leak in a heater core hose not a blowout.

 

I'll give that a try, thanks

 

Putting teflon tape (pipe seal tape you speak of) would definately prevent it from grounding. The switches are dryseals and don't require anything to seal em. Also, once that's done and the fans still don't turn on at 220, wait a bit longer to see what happens. Also, burp all the from the system (idle the car with the rad cap off and fill as needed). Pressurized air is most likely the reason for your cap poppin off.

 

Neither teflon tape nor a liquid sealer prevents the switch from grounding. It doesn't matter if the threads on the switch are NPTF, the threads in the block are NPT, so a sealer is still required. Sealers are recommended with NPTF anyway to fill voids and prevent galling.

 

New Cap Heater Core Control Valve REPLACE THAT!! they all brake ive worked on 4 of them from factory they will break if you even hold it get a erplacment new radiator thermostat? umm fans a cap?? that won't do much.

 

Replace your radiator cap. It costs like $3, maybe, and should routinely be replaced anyway. As they get old they will fail to hold the pressure in the system as temps rise above boiling and.....coolant will spew out of the reservoir.

Don't leave your fan running continuously. There's absolutely no reason for it. Your motor runs fine at temps above 200 and a fan on temp near 220 is perfectly fine.

Water, which is a product of combustion, creates acids when mixed with oil. A motor needs to get hot enough to boil this water out of the oil before acids, and resulting sludge, are produced.

Not real sure what a 'fans a cap' is?

 

Wouldn't layers of teflon tape make the switch not make contact with the block? Just wondering. I didn't put any when I installed my stuff. No notice of leaks so far.