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Odd Coolant Leak in 2.2L, 4 Cylinder S-10


whitedavidp
11-24-2007, 01:13 PM
Hello. I recently came into posession of a 1995 S-10 pickup with the 2.2L engine. It was a California car but is in Seattle now. My dad gave it to me (nice guy) but he warned me that it has a persistent coolant leak that he could never figure out. In the couple months I have had it, I had not noticed any dripping or coolant loss. But recently this has changed.

Last week, the vehicle started running rough. So I went to pull the plugs. I found that try as I might, I could not get a grip on the #3 plug. I slowly chipped away a greenish crud from around the plug hex. Finally, I was able to grab the plug enough to pull it out. I replaced the plugs and wires and the truck runs great again.

However, the coolant leak is more noticable than before. Every time I get out of the cab after driving, I can smell the coolant vaporizing. But I have not been able to see any souce of this. I park the truck over a drip pan with newspaper and the next morning I can see a puddle of coolant on the paper - maybe 4-5 ounces. But still, I can see no source of the leak.

I am assuming that the crud that came out from around the #3 plug was crystalized coolant because it was greenish. So I am thinking that there is a slow leak somewhere above or near the #3 plug and that the cooland evaporates leaving the crud behind. Perhaps as the crud builds up, the leak slows down. But from where could this coolant be coming? I'd think I could see something but no...

I have put in some leak-stop for radiators. I did not think it would help but what the heck. No joy as expected. So now I am stuck trying to find/fix the source of this leak.

Anyone have any suggestions? Thanks.

sickcallawayc12
11-24-2007, 08:41 PM
It could be the intake manifold gasket, I don't know much about the S-Series 4 banger though. It is a pretty tough leak to spot and is one of many, many GM vehicles that share this problem. I'm thinking some sort of gasket is shot regardless.

MT-2500
11-25-2007, 08:50 AM
Welcome to AF.
To fix the leak you are going to have to find it.
Clean off engine and around the plugs and where there is the coolant crud is.

Then start watching that area for wetness.

Some leaks leak hot or warm or cold.
Check at all 3 temptures.
Also a rad pressure pump helps spot leaks or some leak dye in coolant.
Post back what you find.
MT

whitedavidp
11-25-2007, 12:41 PM
It could be the intake manifold gasket, I don't know much about the S-Series 4 banger though. It is a pretty tough leak to spot and is one of many, many GM vehicles that share this problem. I'm thinking some sort of gasket is shot regardless.
Thanks for the response. But since the intake is on the right and the plugs are on the left, I don't see how it could be an intake gasket leak if my theory that the green crud is indeed coolant is true. The leak could not "jump" over the rocket cover without leaving some trail.

Also, are there any water ports that are sealed with intake (or exhaust for that matter) gaskets? I don't know but I'd think not. I do note that the heater hoses run over the rocker cover above plug #4 and I suppose that could be a source. But I would expect to see some crud around #4 plug as well. I do not.

I would question the head gasket but since it is below the plugs I again cannot see how the coolant could "jump" up into the #3 plug hole (and not elsewhere).

I am worried that what this may be is a crack in the head itself. I don't know if any water ports run above the plug holes. But if one did above plug #3, it could leak right into the plug hole. I sure this does NOT turn out to be the case.

I also note that, on close inspection, the outer (visible) surface of the exhaust manifold seems slight tinged in green. I wonder if this too could be residue from coolant? If so and the leak runs down the exhaust manifold, this could explain why the puddle under the car is way back under the seats rather than up front under the engine.

whitedavidp
11-25-2007, 12:44 PM
Welcome to AF.
To fix the leak you are going to have to find it.
Clean off engine and around the plugs and where there is the coolant crud is.

Then start watching that area for wetness.

Some leaks leak hot or warm or cold.
Check at all 3 temptures.
Also a rad pressure pump helps spot leaks or some leak dye in coolant.
Post back what you find.
MT

I agree that finding the leak has to be the first step. I have, of course, been doing this but perhaps not adequately. I like the idea of a cooling system pressure test and the leak dye is a good idea too. I guess it is off to the parts store for both. I hope I can rent a pressure tester rather than purchase one.

I will report what I find. In the meantime, I wonder if anyone can speak to the likelihood of a head crack causing the leak? I find it hard to believe that this is a common problem but maybe others have experienced it.

sickcallawayc12
11-25-2007, 02:44 PM
You should be able to rent a pressure tester from a parts store. A cracked head is possible, but I don't think it happens too often with these trucks. Has happened to me on other 4 cylinder vehicles with aluminum heads, never on a Blazer or S-10 though.

MrWrongsalive
11-27-2007, 01:56 PM
Hi, I just came into posession of a 2000 S-10 with a 2.2. I have been noticing the same style of coolant leak that you have. My leak is in the #1 cylinder. The coolant seems to be building up in the spark plug recess and saturating the exhaust manifold gasket but only in cylinder #1. Every so often I can barely make out the smell of burning antifreeze. I did notice a small amount of coolant build up underneath the exhaust port.
In my research into this matter, I have uncovered a couple of possibilities I plan to investigate.
The first thing I keep hearing is that the intake manifold gasket could be the problem. Even though they're on opposite sides of the engine, if there was a coolant jacket that circulates through the intake manifold gasket that could introduce coolant in to that intake runner. The problem there is that the #1 plug doesn't show any evidence of burning coolant and there is no smoke out the tail pipe. Another odd thing is that I noticed someone had installed air craft clamps on the coolant hoses in that area, perhaps its an old leak, perhaps not. I'll keep you aprised of what I find, if you hear anything let me know.

MrWrongsalive
12-16-2007, 11:19 PM
Ok, here is what I discovered so far. The intake manifold is not possible, there are no coolant jackets located near the #1 cylinder intake port.
I cleaned off the engine and got all the coolant out of the plug port. After I drove the truck down the highway for 160 miles I checked the plug hole and sure enough clean coolant was back again. It was dribbiling down the side and saturating the exhaust manifold gasket. I plan to run a leak down test on the #1 cylinder this coming weekend to determine if the coolant is in the cylinder or in the threads for the spark plug.

MT-2500
12-17-2007, 08:28 AM
Ok, here is what I discovered so far. The intake manifold is not possible, there are no coolant jackets located near the #1 cylinder intake port.
I cleaned off the engine and got all the coolant out of the plug port. After I drove the truck down the highway for 160 miles I checked the plug hole and sure enough clean coolant was back again. It was dribbiling down the side and saturating the exhaust manifold gasket. I plan to run a leak down test on the #1 cylinder this coming weekend to determine if the coolant is in the cylinder or in the threads for the spark plug.

If it is external leak it may not show on a cylinder pressure test.

Try a rad pressure test also.
It sounds like a external head crack.
Good luck
MT

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