Head gasket, or???

[dj1111]

My daughters '90 Camry (4 cyl) has developed a bad coolant leak at the top rear, drivers side of the engine. At first I thought it was one of the rubber coolant hoses that all meet together in that area of the engine. But it was parked outside in very cold weather at the time I took a look at it so I had limited ability to diagnose it. Wherever it is leaking from you cannot see it from any view angles looking from the top down. She later took it to a shop where some friends work and they said it is her head gasket. It is a reputable shop but I always question a first diagnosis at least once. The engine still runs fine. No check engine lights. No miss firing. But it leaks coolant quite profusely. I haven't taken a close look at it yet. Is there any other place it could be leaking from in that area of the engine? Other than the head gasket?

[Brian R.]

Use a mirror and a light to get a good look. There might be a freeze plug in that area.

[dj1111]

I'll have to get it over to my house and into the garage. It would be nice if it was a simple as a freeze plug. Her coolant was very rusty in color. Also, when I start adding coolant to the radiator, and as the engine fills to the leak level, it will start leaking at a very fast drip, drip, drip rate. If anyone else reading this thread knows for sure if a plug is in that area please respond.

[dj1111]

No freeze plugs in the area. I went to the local Toyota Dealer and had them print a copy of the block and head, pointing to what is what and where. I was starting to lean towards the head gasket again after looking at the prints.

Tonight I finally had time to get over to take a look at it. In a beautiful dark, cold, foggy, misty Wisconsin evening. Turns out it is one of those steel coolant tubes that runs from the water pump across the front of the engine. One of them turns back to behind the distributor to what I figure is a heater hose. There's also a littler one that splits off from it, that's the one that's leaking. It doesn't look like too big of a pain to change it. But I think a person would have to remove the exhaust manifold to do the job.

Has anyone replaced this pair of tubes and knows the procedure?

The daughter's going back to the shop that told her it was the head gasket to see what they'd charge. In their defense it does look like her head gasket is oozing a bit down the front of the engine. It's been that way for years now. But it isn't where the profuse leaking is going on. I'm going to stop at the Toyota shop to see what the part would cost me (Update $118.).

[dj1111]

Last word on this one. I finally got to work on her car. The small steel tube that was leaking coolant had plenty of clean (non-leaking) tube left on it. So I purchased a 1 foot length of rubber hose that was about 3" longer than the one currently in use and simply pushed it much further up the steel tube to cover the leak. Then added 2 clamps one where it normally would be just inside the flare of the steel tube, and one at the very end of the rubber hose to seal off any leaking. It worked perfect. No leaks and the car now runs great with a full cooling system. Total cost including about 3/4 gallon of anifreeze, less than $10. For a woman that could ill afford a new car or the $700. head gasket repair, she's one happy camper.

[Brian R.]

Great job!

[Chapol]

Can you perform the same magic on my 1990 V6 Camry? Can't seem to find a leak, but can't keep coolant in the engine.

[dj1111]

You didn't mention, is it dripping on the ground? O getting eatin' up inside the engine.

[Toysrme]

Find the leak. If it's externial, you can see it.
If it's internal (Blown head gasket) you'll get white smoke out the exhaust & low compression, normally heavy moisture contamination in the oil which will destroy all bearing surfaces if you don't change it.




Do a compression / leak down test & see if it's a blown head gasket. If you've blown the head gasket, check that the heads are not warped.

[Brian R.]

Toysrme - Does a blown head gasket always show up with a lower compression?

[Toysrme]

Yep. It's more obvious on a cylinder leak down test, but a compression test will show the problem. Here's an example I had from awhile back:

Toyota's minimum compression is a universal 142psi. On this example, the normal compression spec is 168psi. My personal opinion, any non turbo/supercharged Toyota engine under around 155psi spells some kind of problemb brewing. Poor ring/ring land seal, valve seal/valve timing, etc. Anything under 150psi is a 100% problem. Bad ring seal, or blow head gasket


This is the 3.0L 3vz-e SOHC v6 installed in the truck/suv's from 87-95.

Piston - Compression in psi
1 - 150
3 - 30
5 - 145

2 - 120
4 - 135
6 - 140

So on the right hand bank (Rear bank on a transver v6 i.e. sideways front wheel drive)
On cylinders 1-3-5 you can see 1 and 5 still meet minimum compression, however cylinder 3 (in between cylinder 1-5) has no compresson.
Cylinder 3's head gasket is obviously blown as ring's normally wear about the same rate.
On cylinders 2-4-6 (left hand / front bank) you can see that no cylinder meets minimum compression.
Cylinders 2 & 4 have a blown head gasket that has blown inbetween the clylinders. While cylinder 6 is not blown, the heads have warped, and are causing low compression.


I told the guy that & was right.





Leakdown tests are more obvious when it comes to rings VS head gasket VS block warping, but it takes very little deductive reasoning with a compression test to come to the same conclusion.



THE ENGINE MUST BE WARM.
If it's not warm, the rings won't seal, the valves won't seal perfectly, nothing will seal. The measurements will be all across the board & be mostly meaningless.

[Brian R.]

I guess my question was whether you had ever heard of a bad head gasket that wasn't leaking into a cylinder.

[Toysrme]

You can blow a head gasket externally & not at a coolant, or oil leak.
That can happen every now & again, like. If a lot of carbon is built up in one area. It'll superheat & can burn through the fire ring, warp, or lift the head/block apart & then it just torches everything behind the firering.

What happens like 90% of the time, is that you blow the head gasket directly going to a coolant passage. Coolany flow will get low, or uneven & a cylinder will start to overheat. Sometimes it burns straight through a fire ring, but a lot of times the head / block will stretch laterally apart shearing the gasket, warp, or lift & then it'll toast itself to the coolant passage nearly instantly.

That's what happens like 90% of the time. Then msot of the time that happens the water mixes with the oil.

Even if you don't blow it directly to an oil passage, if they left, stretch, or warp the oil & coolant can mix & even if the oil stays good, the coolant in the combustion chamber will go right past the rings into the oil. If you run it for awhile the coolant will clean the oil off the cylinder walls & kill the rings. Then it'll just pour into the crankcase.



But ya, there are a few times where you can blow a head gasket & not be leaking coolant, or oil.

[Brian R.]

Thanks for the discussion