Coolant woes... again

[ozzyleven]

A little while back, my 94 3.0 was smoking somewhere behind the engine because of coolant hitting the crossover. I replaced a couple hoses on the driver's side that were clearly leaking (forget the names of them) and the problem went away. Even went on a 2,000 mile trip with no leaks or smoke. The other day it came back and now the smoking is much worse. No loss of performance or overheating. I just keep topping off the coolant.

My gut says its the hoses right behind the intake, but I can't see them. I fail to see how you can get to any of it without removing the intake. If I were to remove the intake how much time am I looking at for the job? Also I know there is some sort of gasket where the sensor bank is. Is that a RTV job or is there an actual gasket with a name? Any other gaskets that are required to remove the intake and reassemble? I'd like to have all the parts handy before I tear into it. Either that, or how much should I expect a shop to charge to replace all hoses back there? My patience is wearing thin. Every time I fix a leak a couple more appear. Thanks for any help! As always its appreciated.

 

[DC runner]

Hi temp RTV exceeds the gasket temperature. That doesn't mean that a pre-shaped gasket isn't superior in terms of ease of use, but the RTV silicon HI Temp is designed for engine use.

I use RTV for just about everything honestly.

 

[ozzyleven]

So the runner passed a coolant pressure and compression test at the mechanics shop the other day. Yet, I still am loosing lots of coolant and getting smoke near the firewall (its hitting the crossover). You can see coolant running down onto the bell housing and driveshaft. No visible leaks back there though when looking from the top. Has the mechanic as confused as me. Anyone have any thoughts where to look for this leak? Head gasket, freeze plug, or the seal on the coolant sensor bank? Its going back to the shop tomorrow for more digging around. From what I have gathered, all possibilities will be a pain in the ass and somewhat costly to fix.

 

[BucknutBob]

Has anyone tried holding one of those small extension mirrors behind the sensor area (the coolant bypass block at the rear of the intake) while it's running? It might be as simple as a pinhole in one of those small hoses back there. Just a thought.

 

[ozzyleven]

Yeah, its all been checked out back there. Hood was pulled off to get a better view. That little U-shaped hose was just replaced (first attempt at fixing it). Plus, the leak is much more than a pinhole. Its losing about a pint of coolant every 5-10 minutes, but most of it is burning up and creating ridiculous amounts of smoke. Shouldn't a leak that significant show up on a coolant pressure test? You would think it would be obvious, but no one wants to stick their head in the toxic cloud when its running and the only traces you see when turned off are on the undercarriage.

 

[ozzyleven]

Well, turns out my leak was where the coolant sensor attaches to the engine. Intake off and on and new seal cost me $260. After an hour of driving, one of the heater lines sprung a leak. $16 fixed that. This morning, couple month old, idler pulley started seeping coolant. So, I guess the timing cover gets to come off next... Any possibility that something could be causing my cooling system to over-pressurize and cause leaks?

 

[SV_Dude]

Your radiator cap may be bad. They are supposed to release pressure into your overflow tank when the fluid gets hot and builds up pressure. Are you getting any coolant in your overflow tank?

 

[ozzyleven]

Yeah I get coolant in the overflow and the level goes up and down, so I'm pretty sure that it gets taken up and left behind when needed. I'll probably just replace the rad. cap anyways just to be safe. It may be original, its marked in Japanese anyways. Best to just stick with a Toyota rad. cap, or will aftermarket be fine? Also, I started getting a code 71 (EGR CEL) yesterday. I reset the comp. and it comes back after about 5 miles. Any way all this could be related?