Coolant Leak...
Powerarranger
03-12-2006, 05:07 PM
Hey, everybody...
I have a '93 Jimmy SLE (2wd vin W) that I was given for free last summer. It had a multitude of the usual problems that the previous owner (a close friend) couldn't deal with. I've fixed pretty much everything except for an annoying coolant leak, and this one has me a little stumped.
The main leak is coming from the center drivers' side freeze plug. It's impossible to reach because the motor mount is located right in front of the plug. The coolant drips along the oil tubes and filter, and blows back to the transmission pan.
The second leak is more mysterious. There is a drip of coolant that is collecting at the bottom of the timing chain cover - it looks as if it were coming from inside, but there's no water in the oil. Any guesses where this could be coming from? Perhaps the lower intake? I replaced the water pump last summer, along with the radiator.
I know for a fact that this engine severely overheated several years ago. The radiator drain plug blew out and my friend drove the car for several miles before he stopped. It's had the coolant leak ever since.
This is a great truck and is now my daily driver. Even though it has 207K on the clock, it runs great and gets 20-25 MPG. I'm going to be taking some time from work and will have access to another car for a few weeks, so I'm going to have a go at this.
Right now, I'm considering pulling the engine so I have more access, esp. to that freeze plug. Compression is consistent across all cylinders, but could it still be a head gasket? I have a feeling I'll be opening Pandora's box when I start tearing into the upper end, especially since it overheated. If the head gasket(s) need to be replaced, I'll definitely want to have those milled. What about the lower intake? Is there a way to check for warpage of those mating surfaces?
Sorry this got so long. Work may start this Wednesday or maybe a week later, but I wanted to get some input from you fine folks before I roll up my sleeves...
I have a '93 Jimmy SLE (2wd vin W) that I was given for free last summer. It had a multitude of the usual problems that the previous owner (a close friend) couldn't deal with. I've fixed pretty much everything except for an annoying coolant leak, and this one has me a little stumped.
The main leak is coming from the center drivers' side freeze plug. It's impossible to reach because the motor mount is located right in front of the plug. The coolant drips along the oil tubes and filter, and blows back to the transmission pan.
The second leak is more mysterious. There is a drip of coolant that is collecting at the bottom of the timing chain cover - it looks as if it were coming from inside, but there's no water in the oil. Any guesses where this could be coming from? Perhaps the lower intake? I replaced the water pump last summer, along with the radiator.
I know for a fact that this engine severely overheated several years ago. The radiator drain plug blew out and my friend drove the car for several miles before he stopped. It's had the coolant leak ever since.
This is a great truck and is now my daily driver. Even though it has 207K on the clock, it runs great and gets 20-25 MPG. I'm going to be taking some time from work and will have access to another car for a few weeks, so I'm going to have a go at this.
Right now, I'm considering pulling the engine so I have more access, esp. to that freeze plug. Compression is consistent across all cylinders, but could it still be a head gasket? I have a feeling I'll be opening Pandora's box when I start tearing into the upper end, especially since it overheated. If the head gasket(s) need to be replaced, I'll definitely want to have those milled. What about the lower intake? Is there a way to check for warpage of those mating surfaces?
Sorry this got so long. Work may start this Wednesday or maybe a week later, but I wanted to get some input from you fine folks before I roll up my sleeves...
old_master
03-12-2006, 05:59 PM
A little sweat equity never hurt anyone! I will try to address each issue you have.
The coolant leak by the motor mount can be accessed by jacking up the engine and removing the motor mount. Working through the wheel well may allow a better angle at the core plug.
The coolant leak in front may be the intake gasket, or a water pump gasket. A cooling system pressure tester would help locate exactly what is leaking. Some of the auto parts stores have a "loan a tool" program and there is no net cost involved.
Consistent compression indicates the head gaskets, rings, and valves are sealing. That is all a compression test accomplishes. A compression test does not check for any other head gasket issues such as leaking oil passages, leaking coolant passages, or leaking oil or coolant externally. So, to answer your question about head gaskets: their ability to seal the combustion chambers appears to be good. There are oil feed and return passages and coolant passages that go through the head gaskets as well. A cooling system pressure test will determine if the coolant passages are good. The coolant will either leak externally or into the oil. If oil is present in the coolant, a head gasket could be the culprit.
A machine shop will be able to check for any warp to the heads and the intake manifold.
Pulling the engine is a lot of work. If repairs can be done without pulling it, go for it! If I missed something, let me know.
The coolant leak by the motor mount can be accessed by jacking up the engine and removing the motor mount. Working through the wheel well may allow a better angle at the core plug.
The coolant leak in front may be the intake gasket, or a water pump gasket. A cooling system pressure tester would help locate exactly what is leaking. Some of the auto parts stores have a "loan a tool" program and there is no net cost involved.
Consistent compression indicates the head gaskets, rings, and valves are sealing. That is all a compression test accomplishes. A compression test does not check for any other head gasket issues such as leaking oil passages, leaking coolant passages, or leaking oil or coolant externally. So, to answer your question about head gaskets: their ability to seal the combustion chambers appears to be good. There are oil feed and return passages and coolant passages that go through the head gaskets as well. A cooling system pressure test will determine if the coolant passages are good. The coolant will either leak externally or into the oil. If oil is present in the coolant, a head gasket could be the culprit.
A machine shop will be able to check for any warp to the heads and the intake manifold.
Pulling the engine is a lot of work. If repairs can be done without pulling it, go for it! If I missed something, let me know.
Powerarranger
03-12-2006, 06:29 PM
I agree, pulling the engine is a lot of work. I'd like to avoid it if possible.
The reason I brought it up is because I'll have to jack the motor up quite a bit to get the proper angle for that freeze plug, even with the motor mount removed. One whack in the wrong spot could turn this job into a nightmare! There's not enough room to use a puller (as far as I can tell by what I've seen) so I was going to try and pivot the plug out if I left the motor in the truck.
Great idea about the pressure tester! I have access to one and that will be the first thing I do. The front leak is very hard to spot because of all the hardware on the front of the engine. I could have gotten a poor seal on the pump gasket when I installed the new one - I hope that's all it is. I've heard that the intake manifolds on these engines (vortecs) are prone to leaking. Are there any tips to prevent this if I have to replace the gasket?
Thanks muchly!
The reason I brought it up is because I'll have to jack the motor up quite a bit to get the proper angle for that freeze plug, even with the motor mount removed. One whack in the wrong spot could turn this job into a nightmare! There's not enough room to use a puller (as far as I can tell by what I've seen) so I was going to try and pivot the plug out if I left the motor in the truck.
Great idea about the pressure tester! I have access to one and that will be the first thing I do. The front leak is very hard to spot because of all the hardware on the front of the engine. I could have gotten a poor seal on the pump gasket when I installed the new one - I hope that's all it is. I've heard that the intake manifolds on these engines (vortecs) are prone to leaking. Are there any tips to prevent this if I have to replace the gasket?
Thanks muchly!
old_master
03-12-2006, 06:48 PM
Correct me if I'm wrong here, but I believe your '93 has throttle body injection, in which case, intake gasket replacement is straight forward. Just a dab of RTV in the corners of the intake will help. Just make sure the RTV is "oxygen sensor friendly". The parts store will tell you which ones are.
Also, don't be overly concerned about totally removing the core plug. I have taken many engines apart and found core plugs inside the block. The ONLY reason core plugs are used is to close the external hole in the block after the sand casting, (manufacturing) process of the block is complete. The hole is used to remove sand and the void that is created is used as a coolant "jacket" around the cylinder wall. It is not there for freeze protection. There is plenty of room inside the block for it to rest without causing any harm. If it's aluminum, it can't rust. If it's steel, it needs oxygen to rust. So if you end up pushing it into the block, don't worry about it.
Also, don't be overly concerned about totally removing the core plug. I have taken many engines apart and found core plugs inside the block. The ONLY reason core plugs are used is to close the external hole in the block after the sand casting, (manufacturing) process of the block is complete. The hole is used to remove sand and the void that is created is used as a coolant "jacket" around the cylinder wall. It is not there for freeze protection. There is plenty of room inside the block for it to rest without causing any harm. If it's aluminum, it can't rust. If it's steel, it needs oxygen to rust. So if you end up pushing it into the block, don't worry about it.
Powerarranger
03-12-2006, 08:18 PM
Actually, this engine does in fact have the cpi system, which has been replaced. I only removed the upper plenum and didn't really notice a coolant leak. Wasn't really looking for one at the time, though.
Thanks for the information about the core plugs - I always called 'em 'freeze plugs' because I thought they were to prevent the block from cracking if the coolant were to freeze - they would pop out sacrificially and let you know you had a problem. Must be an old wives' (mechanic's) tale.
I also thought that a lost core plug would cause a hot spot in the block and cause cooling problems later. If you think it won't cause a problem, then I won't worry about it.
I never knew that they used sand in the casting of the block - never really thought about it, I guess. Thanks to you, I learned something today! :)
Thanks for the information about the core plugs - I always called 'em 'freeze plugs' because I thought they were to prevent the block from cracking if the coolant were to freeze - they would pop out sacrificially and let you know you had a problem. Must be an old wives' (mechanic's) tale.
I also thought that a lost core plug would cause a hot spot in the block and cause cooling problems later. If you think it won't cause a problem, then I won't worry about it.
I never knew that they used sand in the casting of the block - never really thought about it, I guess. Thanks to you, I learned something today! :)
blazes9395
03-13-2006, 10:13 AM
The second leak is more mysterious. There is a drip of coolant that is collecting at the bottom of the timing chain cover - it looks as if it were coming from inside, but there's no water in the oil. Any guesses where this could be coming from? Perhaps the lower intake? I replaced the water pump last summer, along with the radiator.
Sorry this got so long. Work may start this Wednesday or maybe a week later, but I wanted to get some input from you fine folks before I roll up my sleeves...
W code engine has the thermostat housing located right in front of the intake, on the side not the top, but side and right on top of the timing chain cover. It could be leaking from either the thermostat housing to intake seal, or just simply from the hose that connects to the thermostat housing. If the thermostat is old and hasnt been removed, it is sealed by a little rubber gasket that is on the thermostat itself. If its been there for awhile, this little gasket disintegrates and leaks. The coolant will travel and collect under the timing chain cover, just as you described.
Sorry this got so long. Work may start this Wednesday or maybe a week later, but I wanted to get some input from you fine folks before I roll up my sleeves...
W code engine has the thermostat housing located right in front of the intake, on the side not the top, but side and right on top of the timing chain cover. It could be leaking from either the thermostat housing to intake seal, or just simply from the hose that connects to the thermostat housing. If the thermostat is old and hasnt been removed, it is sealed by a little rubber gasket that is on the thermostat itself. If its been there for awhile, this little gasket disintegrates and leaks. The coolant will travel and collect under the timing chain cover, just as you described.
Powerarranger
03-22-2006, 09:31 PM
OK, started the gory work today. What a mess! First time posting pix, hope this works!
As you can see, the front leak is pretty substantial:
http://img155.imageshack.us/img155/7794/frontleak4iv.jpg
There's also a pretty good leak from the passenger side rear core plug. Found this after removing the starter:
http://img522.imageshack.us/img522/8584/psleak3wu.jpg
A closeup of the main leak, driver's side core plug behind the motor mount...
http://img155.imageshack.us/img155/2400/dscoreleak8pa.jpg
Jacking up the motor...
http://img129.imageshack.us/img129/8231/motorjack3qz.jpg
I'm going to replace the motor mounts with new. Autozone recommended a compression-type plug that you press into place by hand and then tighten a nut to compress a rubber boot to make a seal. Anyone have any luck with these? I'm planning on just using good old plugs and Permatex. The rubber boot thing seems shady to me, but there's not a lot of room to swing a hammer down there.
More pix tomorrow!
As you can see, the front leak is pretty substantial:
http://img155.imageshack.us/img155/7794/frontleak4iv.jpg
There's also a pretty good leak from the passenger side rear core plug. Found this after removing the starter:
http://img522.imageshack.us/img522/8584/psleak3wu.jpg
A closeup of the main leak, driver's side core plug behind the motor mount...
http://img155.imageshack.us/img155/2400/dscoreleak8pa.jpg
Jacking up the motor...
http://img129.imageshack.us/img129/8231/motorjack3qz.jpg
I'm going to replace the motor mounts with new. Autozone recommended a compression-type plug that you press into place by hand and then tighten a nut to compress a rubber boot to make a seal. Anyone have any luck with these? I'm planning on just using good old plugs and Permatex. The rubber boot thing seems shady to me, but there's not a lot of room to swing a hammer down there.
More pix tomorrow!
Powerarranger
03-22-2006, 09:40 PM
BTW, Blazes - you were absolutely correct about the thermostat housing leak. I forgot to snap a picture of it, but the housing is leaking like a sieve. I'm replacing the gasket tomorrow. I'll know then if the seal on the thermostat itself is bad as well.
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