How can I diagnose a possible head gasket issue?

4sefed · **Posted:** Sat Mar 05, 2011 11:25 am

I'm losing coolant slowly, it's harder to start in the cold, i'm sure I can smell coolant when it's cold though the ait vents.

now with that said, i havn't had a chance to get it inside and look for any external leaks. I will be home in a couple of days and will be able to have a look...

it could be a combination of an external coolant leak and air in the filter head. although the air thing seems unlikley as it has kinda been hard to start all of a sudden... it hasn't been a gradual thing...

all winter long didn't really matter how cold it was, turn the key wait til the light went out and crank it over... it would always fire. now when it's cold it will fire on a couple of cylinders and then quit... it will do this a few times and then finally fire and keep running...

Any thoughts or suggestions are welcome.

Grannysgoat · **Posted:** Sat Mar 05, 2011 12:29 pm

You will need to do a leak down test.

racertracer · **Posted:** Sat Mar 05, 2011 2:23 pm

Check for white smoke out the tail pipe when you first start it.

Pressure test the cooling system.

I had a slow leak that was difficult to find. I used a radiator pressure tester that I rented from AutoZone and noticed small drips around the 3/8" spring clamps on the top and bottom of the plastic coolant reservoir that were hard to detect unless you feel around there with your hands.

I replaced the clamps with 3/8" strap clamps and the problem went away.

It only leaked when the engine was Hot and the coolant reached high presssure.

Grannysgoat · **Posted:** Sat Mar 05, 2011 4:45 pm

Also, since you mention that you smell coolant from the heater ducts when you turn it on check your heater coolant coil. This should show up with the coolant system pressure test noted on racertracers reply.

ATXKJ · **Posted:** Sat Mar 05, 2011 5:28 pm

Don't forget - you have an oil/water oil cooler -on the block- under the turbo
mine blew a gasket and leaked oil into the cooling system.

warp2diesel · **Posted:** Sat Mar 05, 2011 6:17 pm

Since the chemical head gasket leak detectors used on gassers don't work on diesels, there are other tricks that need to be used. On mostly older VW IDI diesels made before 1981, there would be a quick rise in cooling system pressure and very small bubbles. With the newer stretch bolts, the problem went away.
All the places to mentioned to check in this thread are good places to check for leaks.
Your heater core, since you smell it, might also be a good place to check including the hose clamps. Where the water drips out of the AC evaporator in summer should be where it would drip coolant if you have a bad heater core.
Another possibility would be the water pump seal.
Also the hoses or clamps to the EGR valve can leak, or the EGR valve can leak.

Here is a check you can do that I have done before. Open the hood and with a glove on squeeze a radiator hose going to the radiator, not the intercooler hose. Start up the engine and do a hard acceleration around the block or about 1/5mile, pull over, open the hood. With a glove on, squeeze the hose again. If the hose is real hard (like Viagra Hard) indicating high cooling system pressure, you may have a problem. If not chances are you just have a stray leak.

Your starting problem sounds more like glow plugs or a small amount of air in the fuel. I came up with and have used the same trick GDE covers (figured it out and then read their thread :banghead:

) on checking glow plugs that is easier than doing it Mopars way :furious:

, so check the threads.
Good Luck

tjkj2002 · **Posted:** Sat Mar 05, 2011 11:03 pm

warp2diesel wrote:

Since the chemical head gasket leak detectors used on gassers don't work on diesels, there are other tricks that need to be used. On mostly older VW IDI diesels made before 1981, there would be a quick rise in cooling system pressure and very small bubbles. With the newer stretch bolts, the problem went away.
All the places to mentioned to check in this thread are good places to check for leaks.
Your heater core, since you smell it, might also be a good place to check including the hose clamps. Where the water drips out of the AC evaporator in summer should be where it would drip coolant if you have a bad heater core.
Another possibility would be the water pump seal.
Also the hoses or clamps to the EGR valve can leak, or the EGR valve can leak.

Here is a check you can do that I have done before. Open the hood and with a glove on squeeze a radiator hose going to the radiator, not the intercooler hose. Start up the engine and do a hard acceleration around the block or about 1/5mile, pull over, open the hood. With a glove on, squeeze the hose again. If the hose is real hard (like Viagra Hard) indicating high cooling system pressure, you may have a problem. If not chances are you just have a stray leak.

Your starting problem sounds more like glow plugs or a small amount of air in the fuel. I came up with and have used the same trick GDE covers (figured it out and then read their thread :banghead:

) on checking glow plugs that is easier than doing it Mopars way :furious:

, so check the threads.
Good Luck

You can use regular "block tests" on diesels,just takes a little longer to confirm only due to diesels putting out less CO2 then a gas engine.They do make block test fluid for diesels also.

http://www.blockchek.com/instructions.htm

GoodCRD · **Posted:** Sat Mar 05, 2011 11:09 pm

It doesn't sound like a head gasket. I would start by checking the fuel filter for being tight. Bleed any excess air out before trying to start the engine and see if that corrects the hard starting issue. If it does you have a leak in your fuel system between the filter and the tank that is sucking in air when your not running. I bet the fuel filter is loose. "Check it when its cold"!

As for your coolant leak, I have to agree with Warpped :cry:

You most likely have a "Cold Water Leak". Check all your connections after the jeep has cooled down and sat in the cold over night. You should be able to see it dripping or wet at the site of the problem. You stated you smell coolant coming out your heat vents. That is where you should start to look. If you do the squeezing of the coolant hose you are looking for coolant flow or "the lack of". You can also use a heat gun to quickly check to see if your thermostats are opening correctly.

And I agree with tjkj2002 that the chemical tests do work on diesels.

Good luck.

4sefed · **Posted:** Tue Mar 08, 2011 3:02 pm

warp2diesel wrote:

Your starting problem sounds more like glow plugs or a small amount of air in the fuel. I came up with and have used the same trick GDE covers (figured it out and then read their thread :banghead:

) on checking glow plugs that is easier than doing it Mopars way :furious:

, so check the threads.
Good Luck

I can't seem to locate the testing procedure for the plugs... can you point me in the right direction? I do recall reading somewhere about testing the resistance of the plugs, but I can't find it in the search..

ATXKJ · **Posted:** Tue Mar 08, 2011 9:20 pm

well #1 on Glow Plugs - you'll have a CEL - if there's no light I'm not sure it's worth testing - but it's simple enough.

1) trace a GP wire up to a 4:1 connector
2) pull 4:1 and measure the resistance each plug to ground
3) good is ~5. to 1.5 ohms (many meters won't read that low)
4) bad is commonly 200+ ohms - although I assume if it reads as a short it's bad (or the meter can't read low enough)

warp2diesel · **Posted:** Tue Mar 08, 2011 9:44 pm

4sefed wrote:

warp2diesel wrote:

Your starting problem sounds more like glow plugs or a small amount of air in the fuel. I came up with and have used the same trick GDE covers (figured it out and then read their thread :banghead:

) on checking glow plugs that is easier than doing it Mopars way :furious:

, so check the threads.
Good Luck

I can't seem to locate the testing procedure for the plugs... can you point me in the right direction? I do recall reading somewhere about testing the resistance of the plugs, but I can't find it in the search..

Unplug the Glow plug controller from the harness, it is not bolted down and located between the battery and brake booster and says BOSCH on it. Go to the wiring diagram in the FSM you down loaded from the Noob section link and the wires will all have color codes. The FSM lists resistance values that drop when the engine is warm. If the reading you get is within range, you are OK. Check out this older post, I had a weird problem:

viewtopic.php?f=5&t=58125&hilit=+Weird

How can I diagnose a possible head gasket issue?

Who is online