Weird cooling problems
 

Ok so here is the deal. Just replaced my hg's and heads on my 3.0 because of the fool I let install my radiator overheated it when he didn't purge the air out of the system. I just got everything back together and I took it on its first drive up the road. First off I noticed a total lack of power. So I took it back to the house and opened the hood only to find a very hot engine. I double checked the temp gauge inside and it was reading normal. The top of the radiator was smoking hot and the intake line was swelling, the but the rest of the radiator was cool all the way to the thermostat. I have a new radiator, electric fan, radiator cap, and thermostat. I have always felt like the cooling system was flawed in that the tstat was after the radiator and cooled coolant hits the tstat causing it to close. If I understand right this would stop the whole coolant systems flow. I had this problem before I changed the heads and assumed it was excess pressure caused by leaking hg's, as a result I went through several tstat's and radiator caps. Any thoughts on this? I remember a couple years ago someone on here had the same problem and recommended a special Toyota tstat with bypass holes in it. I need some input guys. I'm ready to have my baby back on the trail.

Anything guys?

probably an odd thing to suggest, but pull the thermostat and button everything up. then start the engine with the radiator cap off, and keep adding fluid as necessary, and see how things go with your gauge.

if you let the engine idle this way, well after you know things have warmed up, the overheat condition you appear to have seen may meen the HG has blown again if you continue to see bubbles in the radiator

But in its current condition the gauge indicates normal function, why dont I see evidence of the hot engine there?

if the coolant temp sender does not get coolant next to it (from maybe a stuck thermostat, or maybe just a little bit of coolant leaking around the thermostat) it can't give an accurate reading of anything. It's not screwed into the head or block, but relies on water/coolant passing by.

Oh I see, well Im gonna go try removing the thermostat and observe the results. Thanks for the info, I'll report back later.

Ok so here is what I found. My Napa failsafe tstat doubly failed. It failed to open at the correct temp and when this happened it failed to lock open like it was supposed to. So with that changed the cooling problem seems to be solved. Upon driving it down the road once again i found that it still has NO power and the check engine light came on. I popped the hood when I got back and found the crossover was glowing hot on the drivers side(but not on the passenger side. This tells me, if Im correct, that things are running quite lean and/or there may be a blockage in crossover? In the center of the crossover there is a bulge, is this a resonator or pre cat? Is it possibly stopped up? Ive heard of a hot spot there because of the crossover design but this was glowing hot. Oh and the error code was 52, the knock sensor which I just replaced. Any thoughts or ideas? abecedarian?

Are you sure your cat is not plugged? Usually coolant in the exhaust will kill them.

I have a fairly new high flow cat and it wasn't overly hot.

having a new cat doesn't make much of a difference if it overheated once and enough to plug it up.

Ok well off with the cat tomorrow, replace or not?

add a pipe inthere instead

Thats what I am about to do.

If you do that, expect a nasty rotton egg smell from the exhaust. And don't replace the muffler, you will loose performance.

I would replace the cat with a hi-flow aftermarket.

actually, the rotten egg smell would come from a new converter, not a straight pipe.

but if replacing the converter with a straight pipe alleviated the problem, it's fair to assume that the problem was caused by a clogged or otherwise defective cat, no?

Ok so, the cat was stopped up and the timing was way off. Got it a 15 degrees and it runs cool and has more power than ever. My last problem is the knock sensor code and it may just be my imagination but i think i hear a sight miss now that i have open exhaust. It is code 52. I have a newish sensor and wire. I am 99% sure it is not the sensor. Any ideas on how to pin this thing down? Thanks for all the help so far.

Where yall at guys?

*Bump*

it could be a code stuck in there from when it was running poorly... so have you reset the ecu to see if the code returns?