Hi, 94 4runner, 22K on a rebuilt 3.0, (turkeys put in an automatic tranny, gross!). Anyway, it was overheating, no obvious coolant in oil, or visa versa. Replaced the thermostat coupla days ago, compression was 165 all around, garage said a leakdown test with that compression would be a waste of money. I drove a couple hundred miles, OK, fine. Drove to town and then home (2miles uphill) today. The gage didn't read overheating, but when I got home, I looked over at the truck, and coolant was pouring out. Cussed a bunch, threw open the hood, and it had poured out the overflow. Any ideas????

Thanks

 

Likely cause is that the engine compression is leaking out into the coolant passages in the head and overpressuring the cooling system. How to test? Chemical test kit from Napa to check for exhaust gas contamination of the coolant or a pressure test on the cooling system looking for a leak under pressure of for the cooling system pressure to rise with engine RPM/load.

 

is that related to the dread head gasket thang?

 

Typically yes. Coolant flows between the block and the head through the head gasket. Typical leak is between a cylinder and a coolant passage. Might be the gasket is leaking or in my case (22RE) it was a warped head causing the HG not to seal up well enough.

 

Most likely. but could also be a cracked head.
You say there was no coolant in oil/oil in coolant before it overflowed. Is there any now? Most likely once you turn off the engine the coolant will seep through whatever hole is present and get into the combustion chamber or oil pan.

 

There's definitely no coolant in the oil, and it doesn't look like any oil in the coolant. The mechanic pointed out where he fixed a leak yesterday around where the housing goes from the timing chain to the radiator (just remembered when I looked at the engine.)

The radiator cap had some blue linty pieces on it, and the coolant was a little bubbly looking, like it had air in it.

Just assuming the worst, can I transfer a 22re 5 speed into this beast?

 

where in nor cal? Also a 22re swap will be pricey to say the least

 

yeah, a 22re swap would be pricey. Plus, why swap a smaller, older engine in when you could put in a '96+ 3.4L v6?

 

Well... sorry to hear. I was hoping it was just the thermostat (from your other thread).

The cooling system sees usually no more than 12-15 psi pressure, but the cylinders create upwards of 120 psi so you can imagine why you'd have bubbles in the radiator, and why coolant would be blown out of the overflow.

No coolant/smoke out of the exhaust implies it's a small breach and the worst possible damage has not occured. So on the upside you may only need the headgaskets replaced. If it continues to be driven, the coolant loss and overheating will cause the gasket(s) failure to expand and can cause the head(s) to warp requiring expensive repairs.

At this point in time, effecting repair would most likely be less expensive than changing the engine to another compatible one.

However, I do take issue with a mechanic that won't perform a leak-down test when there's evidence there is an issue, and over-pressure in the cooling system is evidence something is wrong. At the very least, the mechanic should have pressure tested the radiator cap and pulled the plugs and pressurized to cooling system to check for coolant leaking into the cylinders. A chemical analysis on the coolant to check for fuel/oil would be wise as well.

 

I'm in Mendocino County, near Willits. I've been reading up on Bars head gasket fix...seems the leak is small, this might do it...maybe, yes?

Yeah, the mechanic is getting old...better find another, but don't know where...

 

I wouldn't do any of those head gasket / coolant leak fixes if I could avoid it. At best you're buying some miles. At worse, you'll have to clean all that out when you fix the problem.

 

x2 on not using the fix-a-leak junk. I used some radiator fix-a-leak about 3 months before my radiator blew. I'm sure the fix a leak stuff contributed greatly to the destruction of my radiator. It clogged a lot of the coolant hoses, and most of it ended up in the overflow and the hose between the overflow and radiator.

 

I talked to Mike who was very helpful, I'm taking the truck in to the mechanic for the leak-down and chemical in coolant test, I hope it's not that, but at least I'll know

I get my other truck back tomorrow from gettin' the timing chain done, I'll just drop off this one at the same time, dog gone it.

 

Hope all goes well and let me know what he quote's you

 

So, we tested the coolant, it's negative for other emissions, did a block test, everything checks out. Any other ideas?

Oh yeah, Abecedarian and all... just wanted to say thanks again to y'all too—not that you hadn't helped, just Mike had taken a bit out of his day at work to talk to me on the phone...

If there is no chemicals in the coolant, should we still do a leakdown test? The mechanic is hesitant, because of the pressure thang...

It hasn't overheated again, either....

 

Got the mechanic to do the leakdown test. He was balking and kicking. #6 cylinder. Bye bye money.

Hopefully the head isn't warped or cracked. We'll see.

 

I still think its time to find a new mechanic sorry