Unexplained coolant loss (4 Viewers)

[Rusty Cruiser]

I have had my 95 for a year now and put 8k miles on it in that time. After I got it, I replaced the radiator, all the cooling hoses, the heater valve, and eliminated the rear heater circuit as I found it to be leaking after replacing all the hoses. I do not have any visible leaks now or smell any coolant while the vehicle is running. With all that said, I have to refill the coolant reservoir about every 1-2 weeks, more frequently if I take a long drive which seems to mean it loses more while it’s running. Is this a strong indication I have a leaking head gasket? It doesn’t smoke any more than normal and it seems to run fine. What is the best way to identify the issue? Pressure test the coolant system? If it does need the head gasket replaced, would it be a good time to rebuild the engine completely? I’m at 280k. I can see if the documentation provided by the prior owner a note referencing “check head gasket job” on a service ticket but I don’t have the invoice showing the actual head gasket job, why it was done, and what else was done at the same time. So the head gasket has been replaced already FWIW.

 

[Malleus]

If you suspect you have a headgasket leak, you should send an oil sample to a lab (Blackstone or someone else) and have it checked. While you're doing that, yes, get a coolant leak tester and do that, too. The gasket can leak into the oil passages or out to the environment, so both should be checked and verified. You can also put some UV dye into the coolant and, if it's leaking out to the air, you should see it, somewhere.

There's no reason to suspect that the bottom end has to be rebuilt, simply because the head needs service. Remember, just because a bunch of nervous ninnies on a website seem to constantly decry the world ending calamity of a blown headgasket, doesn't make it so. Headgaskets were meant to be replaced, and valves do get covered in carbon after a couple of hundred thousand miles, requiring a head removal to clean and reseat them - which in turn requires a headgasket.

This is a normal part of life for an engine and doesn't mean it's in critical condition. In fact, if the head's flat and the valves are clean (I doubt they would be with that many miles, but maybe), you could get by with just a new headgasket. There is a lot that is easier to do with the head off (cleaning the intake and throttle body comes to mind - they have to come off anyway), but that can be postponed if necessary.

Also, the fact that a head gasket may have been replaced doesn't necessarily mean it was the right one. The 1FZ-FE isn't a small block Chevy and you can't get good, reliable replacements parts at the local auto parts store.

If it's just a gasket, and you elect not to do anything but replace it, it's a weekend job - at most. Try not to stress out about it too much. And, if it is a bad gasket, you caught it before it stranded you, so that's a good thing. Best of luck.

 

[Mag71k5]

Be sure and check odd places, mine is leaking out the side of engine where the head and block meet, at cylinder 6. The coolant runs down the engine, and meanders to the frame and would be dry without dripping on the ground.

Also check around the pesky heater hose.

I agree Malleus on how most people make it sound like the end of the world. Hell, I've been driving mine with a known blown head gasket for 5,000 miles or so now. I just keep a watch on my coolant level, and make sure my oil isn't milky and continue mission.

Good luck!

 

[Rusty Cruiser]

I appreciate the info guys! I have requested a sample kit from Blackstone and I will get some UV dye and see if I can find any external leaks. Also well noted even if the head gasket was replaced prior it may not have been done with proper gasket or with the right procedure. The radiator and starter were both replaced prior to me and both were done with non-toyota parts so I wouldn't be surprised if the head gasket was not OEM as well.

 

[thatcabledude]

Would take a little work, but send a video scope through the spark plug holes and see if you find a steam cleaned piston.

 

[ppc]

I would not rule out a slow leak from the PHH - Pesky Heater Hose or leaks from the two lines going to the rear heater.

 

[Tachycardic]

Start with the easiest thing first—the radiator cap. If it has 280k miles on it or anything close, I’d replace it. That was my issue when I had unexplained coolant loss and no obvious evidence of a head gasket failure.

 

[OrangeCrusher]

Does it look like coolant is leaving the overflow bottle? In think that is the most likely place for coolant to escape if you have head gasket issue, in particular if you're saying more is getting lost on longer drives. Pressure in the cylinder is highest, exhaust gases press through the gasket into the coolant system, and blow out via the overflow bottle (taking some coolant with them).
Cheapest test I can think of - tape an empty coke can or similar to the overflow bottle vent hose and see if it catches coolant

If it's going into the oil, you'd probably see milkshake on the dip stick? Actually I have a hard time seeing how coolant would get into the oil - the pressure gradient will almost always be in the opposite direction.