Head Gasket Questions...

[thegadgetguy]

Okay, so basically I'm trying to figure out if my head gasket is leaking before leaving on a 750 mile trip to school next Thursday. Here are the facts:

Bought the truck with 155k miles last year at this time (truck is '97 LX450). Noticed what seemed to be a slightly larger than normal amount of water vapor coming out of the exhaust not too long after purchasing, especially as it got colder. I wouldn't have thought anything of it except that 80s do have a known head gasket problem. Not enough vapor to cause me alarm - just enough to get me thinking.

Fast forward to last week. I checked the overflow bottle - Empty. Then I checked the radiator - can't see any coolant. I know there is some there, because the engine hasn't been running hot (it hasn't been that hot outside, either, 80F maybe) and the "core" or whatever it is that is inside the radiator is wet with coolant. So now I'm trying to figure out where all the coolant went. Just to clarify, at the beginning of the summer, I had noticed the overflow bottle was empty, so I filled it up. I've driven about 700 miles or so since then, so it seems to be a decently quick leak, wherever it is.

This morning, I went to Auto Zone, rented their block tester kit, ran the test in my driveway with the truck at operating temperature, and the fluid did not turn yellow. I'm not exactly sure what to do at the moment - I think I would have a better idea what to do if the fluid had turned yellow, because at least then I would know what the problem is!

I guess my questions would be the following:

1. Is it possible for the block tester kit to fail to identify a leaking head gasket?
2. If the block tester kit failed to identify a leaking head gasket, and the gasket is leaking, is it a bad idea to drive the vehicle next week? (damage to the engine, increased risk of total head gasket failure, etc.) I think the answer to this is yes, but I would just like to confirm.
3. If the head gasket isn't leaking, what would some other possible leak areas be? My truck is Hawaii spec, so no rear heater.

I would really appreciate any insight that you guys might have. This forum has been an incredible resource as I have been fixing various things on my truck, and I definitely could not drive an 80 without it. I'm going to try the test again from a cold start (there seems to be more water vapor out of the exhaust when the block is cold), add more coolant to the system to see if that makes a difference with the block tester, and also look for other coolant leaks. Is there anything else I should be looking for?

Thanks so much,
David

 

[ElCid04]

I'm guessing you haven't noticed any puddles underneath your truck? That's pretty quick for a leak only over 700 miles.

You could also try a compression test kit for confirmation if the block tester doesn't give you any results.

Have you had any maintenance done recently?

Fill it back up with coolant and let it run for 20 minutes while watching for leaks underneath.

I changed my HG a few months ago, and it was a slow leak at first so I babied it, but then one day it completely blew, so you'd be much better off knowing for sure before your long trip.

 

[Brentbba]

Look at the top of your oil fill cap and your oil dipstick. Do either have a light brownish foamy stuff on either? That would absolutely confirm a blown HG with coolant and oil mixing.

2nd the suggestion to fill radiator and overflow bottle and let it run in the driveway for a good while. After my HG I was still loosing coolant at a fairly alarming rate yet oil cap and dipstick were fine, no noticible drips, etc. Eventually found a leak from one of the hoses near the back of the truck but the coolant was burning off as it hit the lower sections of the truck.

Check all your hose connections and your radiator drain cock and engine drain plug for leaks before jumping to a HG conclusion. Good luck.

 

[Ocho77]

^ This.
I had the same problem - emptying the overflow bottle every few days. Found a hose that had a leak and coolant was burning off. It never left a puddle anywhere. Replaced the hose and haven't had to refill coolant in a few thousand miles.

 

[thegadgetguy]

Thanks a lot guys, I really appreciate your thoughts.

I'm guessing you haven't noticed any puddles underneath your truck? That's pretty quick for a leak only over 700 miles.

You could also try a compression test kit for confirmation if the block tester doesn't give you any results.

Have you had any maintenance done recently?

Fill it back up with coolant and let it run for 20 minutes while watching for leaks underneath.

I changed my HG a few months ago, and it was a slow leak at first so I babied it, but then one day it completely blew, so you'd be much better off knowing for sure before your long trip.

I've never noticed any drips other than a whole bunch of ATF everywhere before I rebuilt the PS pump, but that's not saying they weren't there. That's a good idea on the compression test kit. I'll see if I can get my hands on one of those. I've been doing maintenance since I got it (Front axle rebuild, caliper rebuild/brake flush, eradicating 3 CEL codes, PS pump rebuild, replacing suspension bushings, etc.), but obviously none of that really has anything to do with the head gasket or cooling system. I'm going to run to the store and get some more coolant and do as you and Brentbba suggested with letting it run and look for leaks.

Look at the top of your oil fill cap and your oil dipstick. Do either have a light brownish foamy stuff on either? That would absolutely confirm a blown HG with coolant and oil mixing.

2nd the suggestion to fill radiator and overflow bottle and let it run in the driveway for a good while. After my HG I was still loosing coolant at a fairly alarming rate yet oil cap and dipstick were fine, no noticible drips, etc. Eventually found a leak from one of the hoses near the back of the truck but the coolant was burning off as it hit the lower sections of the truck.

Check all your hose connections and your radiator drain cock and engine drain plug for leaks before jumping to a HG conclusion. Good luck.

In answer to your question about the light brownish foamy stuff, I don't think I have any of that, but I did take a few pictures and I will post them so you guys can give a more expert answer. Hopefully that is a good sign!

^ This.
I had the same problem - emptying the overflow bottle every few days. Found a hose that had a leak and coolant was burning off. It never left a puddle anywhere. Replaced the hose and haven't had to refill coolant in a few thousand miles.

I'm hoping it's something like that! Thanks for the information. Do you remember where the hose was?

If it turns out to just be a leak in the coolant system, which I hope it is, do these trucks have a lot of water vapor coming out of the exhaust? Mine definitely has more than any of our other cars. Is it just an older car thing? Thanks so much for your suggestions guys, I can't tell you how much I appreciate it!

 

[half k cruiser]

1) The tester does not always work, I rented one from Autozone and it came back negative on a vehicle with a known blown HG.
2) Figure out where your coolant is going before you drive the truck that far.
3) Sometimes there won't be any sign of contamination on the dipstick or underside of the fill cap, its not a set in stone rule. However if it looks like a milkshake threw up in there then thats a strong sign of a blown HG. Also, you can fill up the rad and the overflow bottle. Look in the overflow bottle while revving up the engine and see if you can see bubbles coming up.
4) There shouldn't be water vapor coming out of the tailpipe.

 

[thegadgetguy]

Okay, here are the pictures as promised.

Oil Dipstick:

Oil Cap:

Valve Cover:

Obviously, I need to change my oil, but I think I will wait until this mess is sorted out...

 

[thegadgetguy]

1) The tester does not always work, I rented one from Autozone and it came back negative on a vehicle with a known blown HG.
2) Figure out where your coolant is going before you drive the truck that far.
3) Sometimes there won't be any sign of contamination on the dipstick or underside of the fill cap, its not a set in stone rule. However if it looks like a milkshake threw up in there then thats a strong sign of a blown HG. Also, you can fill up the rad and the overflow bottle. Look in the overflow bottle while revving up the engine and see if you can see bubbles coming up.
4) There shouldn't be water vapor coming out of the tailpipe.

1. Thanks for the confirmation
2. Understood, definitely won't drive it that far until I figure out the problem, thanks for the input.
3. Okay, good to know. I posted some pictures. I don't think there is any milkshake, but I'll let you guys decide.
4. Hmm. It's worse on start up. I don't know if that helps at all but if the engine is warmed up it's not as bad. I'm going to try the block tester again from a cold start while I look for leaks.

 

[Brentbba]

Certainly doesn't look like you've got any oil and coolant mixing from those pics. That's good news!

 

[1973Guppie]

fill the rad and the overflow carefully as not to cause drips anywhere, get the vehicle up to working temp and sit under there with a flashlight for awhile and I bet you will find your leak. Does not sound like a headgasket issue to me. You are losing coolant somewhere. If all else fails drain your oil and take a close look at it and post pics.

make sure to look at the rear of the engine, phh possibly leaking.....

 

[half k cruiser]

Certainly doesn't look like you've got any oil and coolant mixing from those pics. That's good news!

You don't have to have cross contamination to have a blown HG. My Civic had a blown gasket and never cross contaminated, it would however bubble up the overflow enough to push all of the coolant out over a short drive. I was constantly checking the dipstick and oil cap and never had signs of moisture.

 

[BrotherRob]

I'd be looking for a leak. You can loose a lot of coolant without ever hitting the ground. From what you've shown, it doesn't look like a HG.

 

[toddsmith1]

Isn't one of the byproducts of exhaust going through a catalytic converter H2O? I have 2 97's and I just replaced the HG on one. Both trucks blow white exhaust at startup and it's lessens after the truck warms up. You can tell a big difference when the HG goes. Its a wall of white smoke and does not get better as the truck warms.

 

[thegadgetguy]

Thanks for the comments guys. I'm going out now to fill it up and look for leaks, since that seems to be the consensus. I think I will try the block tester from Auto Zone again once I fill it back up, since I have it.

 

[BrotherRob]

Isn't one of the byproducts of exhaust going through a catalytic converter H2O? I have 2 97's and I just replaced the HG on one. Both trucks blow white exhaust at startup and it's lessens after the truck warms up. You can tell a big difference when the HG goes. Its a wall of white smoke and does not get better as the truck warms.

Depends on how and where they blow. They don't always blow a vapor cloud. Sometimes it's only when cold or only at running temp. I certainly can be both.

 

[Pin_Head]

4) There shouldn't be water vapor coming out of the tailpipe.

Water vapor always comes out of the tail pipe when the engine is running because it is one of the two primary products of combustion.

 

[half k cruiser]

Water vapor always comes out of the tail pipe when the engine is running because it is one of the two primary products of combustion.

It should not be clearly visible during the daytime.

 

[thegadgetguy]

Okay, so I added just under 3 quarts of coolant to the radiator and overflow bottle. Then a friend and I ran the truck in the driveway for over 20 minutes while I looked from the top and he from the bottom for leaks. Maybe half that time was at idle and the second half at like 1500-1600 RPM. We didn't find anything definite. I think the radiator/radiator petcock can be ruled out, as well as the main hose from the block to the radiator and the hose from the radiator to the water pump/thermostat area.

I did attempt the block tester again, but had too much fluid in the radiator and it sucked it up, ruining the test. I'll try that again once I figure out how to get fluid back out of the radiator.

This is just a picture of the radiator before adding coolant. Now that I look at it though there seems to be some build up of something or other on the radiator cap.

Also, I seem to have misspoken when I said there was visible water vapor coming out of the tail pipe. I didn't see any when I was out there just now. I thought it did do that, but I must just be remembering from all the cold weather that we had this past winter. I really haven't gotten to drive the truck much this summer. I apologize if that messed up anyone's diagnoses, though most seem to think a leak more likely than a HG problem anyways.

So I guess the next step is just to keep looking for leaks until I either find something or ? Do you guys have any tips on how to check the PHH? I know generally where it is, but I'm not too clear on how you access it, and I think I'd just burn my hand if tried to stick it in there while the engine was running. I think someone mentioned paper towels in another thread?

Thanks again so much guys,
David

 

[Mighty690]

Blackstone oil analysis.

 

[Pin_Head]

If you are looking for a coolant leak, use a UV or blacklight as the green or red color in the antifreeze is a fluorescent dye.