Looks Like A Head Gasket Leak

[RyanIL]

Hello. A family member bought this 92 LS400 in Tucson a few weeks ago and drove it back to Illinois without any problems. Told me that the heat was blowing cold when stopped in town, so I checked the coolant resevior first.

Empty.

Filled the tank and started. It sucked it down quickly when revving the engine. Thought that if the coolant system was low in the first place, might just need more to get it up to snuff, but it drained it every time.

There's definately white vapor coming out of the exhaust after initial start up, so I don't want to keep putting more coolant in. It's sucking the resevior so fast that it seems like more than a gasket leak would account for, and the oil looks fine (no streaks or white glops). The car has only tried to overhead once, and only for a half second before going back to normal last week. The previous owner said that the "check coolant" light was on all the time before, whether it needed coolant or not.

I'm thinking head gasket here, but wanted to ask some of you with lots of experience before freaking out about it.

Thanks in advance!!

[NewGuy19]

Sounds like it could be a water pump, they are supposed to be replaced every 90,000 miles.

[jcrome04]

Head gaskets do not go out on the 1UZ.

It's very very very VERY rare.

[RyanIL]

Okay, I'll look through the threads for a good way to test the water pump. Sounded loud when I initially started the car, then sucked down 2+ reservoir tanks worth of coolant immediately.

Is it safe to keep adding coolant until it stops depleting; I won't get to change the waterpump until tested and part come in. I've read that the coolant system holds 2.8 gal.

[landar]

ryan, lets back up a moment and go through some troubleshooting 101.

So, coolant in, coolant "disappears". Its has to be going somewhere, right? I would put some newspapers, cloth, tarp, whatever under the car after you have

added coolant and then run the engine up to temp. If the coolant is ending up on the ground, then you will have an external leak which should be fairly easy to find.

If you do NOT have coolant on the ground but it is still disappearing.(...are you a praying person? :) ) then you will have to look for an internal leak.

And if it is internal, you had better find it w/o driving much cause it can destroy your engine quickly. I would keep a vigilant eye on the oil and level.

So where could it be going internally? Well, in some cars (but not a Lexus per se') coolant can get into the combustion chamber via blown gaskets, like the head gasket that you mentioned. But it can also get into the engine by a leaky intake manifold gasket (that would lead to contaminated oil). Now another place that coolant can go (again on some cars but NOT at all likely on an LS) is into the transmission via the radiator. You can check the tranny dipstick just for sanity.

The "white" smoke that you mentioned could be power steering fluid getting sucked into the engine. From what I understand,

it is somewhat common on the LS. On the other hand it COULD be a head gasket BUT as jcrome pointed out, NOT likely (lets hope its not that).

You could run a compression test on all cylinders just as a base line. Might show something. And look carefully at all the plugs if you pull them out. Burning coolant in one

of the cylinders will usually discolor the white insulator more so than on other cylinders. Besides white exhaust, there is usually an unmistakable smell of antifreeze

at the rear of the car. I dont even want to suggest cracked head or block, so I wont ;)

Look for an external leak first. That is most probable.

[SRK]

Fill the engine with water, not coolant. That way, if there is in fact a leak into the cylinders and the oil sump, you won't further contaminate anything.

The white "vapour" is more than likely normal exhaust steam.

You can't diagnose this problem until the entire system is full and the level is noted so you can watch it. If it goes down, and the oil stays clean, then it's the water pump. They go bad, head gaskets do not.

It may be neccessary to pull the front covers off the engine in order to check the weep hole under the pump. And you may also have to pressure test the engine when it is cold.

Diagnose this thing, don't jump to conclusions, would be my advice.

[landar]

Fill the engine with water, not coolant. That way, if there is in fact a leak into the cylinders and the oil sump, you won't further contaminate anything.

The white "vapour" is more than likely normal exhaust steam.

You can't diagnose this problem until the entire system is full and the level is noted so you can watch it. If it goes down, and the oil stays clean, then it's the water pump. They go bad, head gaskets do not.

It may be neccessary to pull the front covers off the engine in order to check the weep hole under the pump. And you may also have to pressure test the engine when it is cold.

Diagnose this thing, don't jump to conclusions, would be my advice.

Well, ok use water... but be careful. It can get cold enough this time of year in Illinois to push freeze plugs. So just make sure the car is back in a warmer(than freezing) garage at night.

[RyanIL]

That's great. I'll keep checking back and post what we find in the end.

Ryan

[MR. LEX]

If you had a Head gasket leak you would smell it. It's a very loud smell and blue smoke would come out the exhaust.

[jcrome04]

A very loud smell huh? ;)

hahah :D

[python]

ya whats a loud smell? anyways i would take it to a shop and have a coolant system leak diag done, then have a block test done

[eatingupblacktop]

Ryan, have you done any of the suggestions offered? Basic check is to make sure you have enough coolant (10.6L). Then run the engine and look for a drop. What have you noticed? It's been a while since you last posted here.

[MR. LEX]

Sorry to all those people who doesn't know what a loud smell means. It means a very strong smell. I'm from the south. I know we speak differently. If you haven't found the leak yet put ink in your coolant. It makes it easier to see where your leak is coming from. Hopes this helps.