97 XJ Burning Coolant In Cylinder 1

Folks, I've been losing coolant, and the plug #1 looks far too clean and smells like antifreeze.

So I removed the head, and the gasket looked fine, but the valves for cylinder 1 looked squeaky clean.

Am I right to expect a cracked head? Do blocks crack frequently on 4.0-liters?

-DT

The most common reason for unexplained fluid loss is an old leaky radiator cap. They should be replaced about every two years. If you were burning antifreeze, you would have buildup on the plugs, not clean plugs.

old_man said:

The most common reason for unexplained fluid loss is an old leaky radiator cap. They should be replaced about every two years. If you were burning antifreeze, you would have buildup on the plugs, not clean plugs.

Click to expand...

There are no coolant puddles under the car.

There doesn't need to be. I had a near constant drip from my thermostat housing and never had fluid hit the ground. The only way to find exactly where it was leaking was to start it, open the hood and rev the motor as it wasn't leaking at idle.

Also, Old_man is right about the plugs.

cavalier said:

Folks, I've been losing coolant, and the plug #1 looks far too clean and smells like antifreeze.

So I removed the head, and the gasket looked fine, but the valves for cylinder 1 looked squeaky clean.

Am I right to expect a cracked head? Do blocks crack frequently on 4.0-liters?

-DT

Click to expand...

Here's a question. Forget squeaky clean, did the valves for cylinder 1 look completely different from the others? Good comparison cylinder would be 6.

If you have the head off, might be worth it to have it pressure tested.

Burning coolant doesn't always leave that nastiness on a plug. If it goes lean, it'll get hot and clean that bastard right off. All that'll be on the plug is tiny little black spots....that's the piston.

The blocks usually crack externally or lose fluid through the freeze plugs. It would likely be obvious. Was there any evidence of coolant in the oil? What did the pistons look like? How much coolant are you losing? Take the head to a machine shop with the old head gasket and have them check it out. At a minimum the head should be planed flat by a machine shop before reassembly. Don't rule out weeping gaskets or hose clamps or hoses as the source of your coolant loss. Like the others have said, if its a small steady leak from a hose it may burn off before it hits the ground. Check around all the hoses, clamps, and gaskets for any traces of coolant residue, like tail marks, etc.

I should mention: the engine is misfiring severely and the oil level is over an inch higher than max on the dipstick. Oil doesn't look too milky except on the very top of the valve cover, which is coffee-ish.

A bad radiator cap actually allows steam to escape. The steam is from the coolant. It actually leaves through the overflow bottle vent. While you are at it, take a look at the back of the valves for buildup.

More times than not if you have a cracked head, the exhaust actually pressurizes the radiator and causes it to boil over after a few minutes of driving. The only exception would be if it is cracked into the intake. That is why a said check the back of the valves. If it is going into the intake, you will find a lot of buildup on the back of the intake valves.

Coffee with one creamer or three? I think you should drop your head and gasket off at a good machine shop and let them check it. Normally they'll magna flux it. In rare cases a head will test good cold but open up when hot. The 4.0's with 0630 heads most commonly have head gasket problems and/or warping though they do crack sometimes.

I'll give you an example. My 97 XJ had been doing fine several months after I bought it, until one day it was warm out and then dropped 60F pretty quick. I noticed cream on my oil filler cap and some folks thought it was the rapid temperature drop. I cleaned it off and it came back. I noticed a couple of drops of coffee in the breather hoses & pulled the head. Head gasket looked OK, though the area between the rear coolant jacket and #6 looked suspicious. The tops of #5 and #6 pistons were whitish IIRC. Cylinder head shop looked at the gasket too, didn't say anything, magna fluxed the head, said it was fine, milled it down, and did a valve job. I put it back on with a new head gasket and no more coolant in the oil. I noticed I'm still losing some coolant but I found some loose radiator hoses so I tightened them up. Time will tell. It was a very slow leak, probably used a quart in a the last 25,000 miles with no signs of coolant in the oil...

Does your oil smell like gasoline? Misfires almost always leaves fuel in the combustion chamber. This fuel goes two places, out the exhaust (the stuff that's still atomized) and plugs up the cat, and the rest runs down the walls, past the rings and ends up in the oil.

I'm sure old man will agree as I'm sure, like me, he has seen it on more than one over-carbed SBC.

The head is off, it should be checked out.

Pictures would help

If you really want to know for sure, take a sample of the oil to your local truck stop and get a oil testing done. They can tell you where to get it done. If there is any leaking into the combustion chamber, some of it will end up in the oil because of blow by. It is also a good way to check the general condition of an engine and to see how it has been running.

iluv83vettes said:

There doesn't need to be. I had a near constant drip from my thermostat housing and never had fluid hit the ground. The only way to find exactly where it was leaking was to start it, open the hood and rev the motor as it wasn't leaking at idle.

Also, Old_man is right about the plugs.

Click to expand...

I have a leaky waterpump gasket. One of these days I'll do something about it. I can always smell coolant but it never hits the ground or even makes it to the oil pan. I add a quart a year of coolant. For that little amount and a leak that isn't getting worse, I'll wait until I have to take the front end apart to take the water pump out.