Cooling Issue and Leak

T

turbobuick

New Member
Joined
Aug 6, 2025
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9
Location
Wheeling, WV
First of all thanks for having me on the forum!

I have a 2010 Sahara with the 3.8L engine and 201k miles. It was starting to get warm (it did not overheat). I noticed the coolant was low so I added some. While I was there I changed the radiator cap as well as the stock cap had some deteriorated rubber. It seems to still be running a little warm (hovering around 230 degrees via the scan tool). I'll be the first to admit I don't know what temperature these are supposed to run.

Anyway I decided to see if I could find the leak. After a bit of searching I believe I found the leak. It appears to be pushing some coolant out between the intake and the head at the front of the passenger side. There is definitely stains on the front of the engine to support this. There is no coolant in the oil.

OK so now for my background. I've been drag racing for about 20 years, off and on. I have a 1987 Buick Grand National that I've had the motor and trans out of multiple times. I tune it with a Holley HP. I also have a 2003 Chevy Silverado 2500HD Duramax that I maintain. Last year I changed the injectors on it as the stockers finally gave up at 198k. I have a full shop to work in and I have an Autel scan tool to deal with the newer cars. We have multiple others car but I won't get into that.

So I guess my questions are:

1. What's the normal operating temperature for these engines?
2. Could a weak water pump have allowed the system to get warm and cause the leak?
3. Is this a known place for leaks to occur?
4. Where do I go next?

Thank you for your time.

----Jer

Jeep-Leak.jpg
 
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Welcome to the forum! I do not have the 3.8 but I do know the temp range is from 195-230. When you hit the 230 mark, is it sitting idle, stop and go traffic or highway? Hopefully someone with the 3.8 can chime in on your other questions.
 
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Welcome! There are quite a few knowledgeable 3.8 owners on here that should be able to point you in the right direction.
 
Is this with the AC on?

Are your cooling fans working and kicking into high speed?

Is your radiator fins clean?

Do you have a big winch or anything else big in front of the grill that could be blocking the air flow.
 
This is with the AC both on and off. Cooling fan is kicking into high and running just fine. Radiator is newish (2 years old) and fins look great. No big winch or anything in the front blocking air flow.

----Jer
 
Did the cooling system get really low and maybe trapped a air pocket in the block?

Maybe try jacking the front of the Jeep up about 6" and take the radiator cap off then idle the engine with the radiator full, watch for coolant to drop and add some more to it.
 
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I can absolutely do that but is that going to address that tiny leak by the intake gasket? It only needed about 1 quart of coolant to fill it back up.

----Jer
 
turbobuick said:
I can absolutely do that but is that going to address that tiny leak by the intake gasket? It only needed about 1 quart of coolant to fill it back up.

----Jer
Click to expand...

No that's not going to fix the leak but it will let you know if a air pocket is your issue.

I and others have had good luck with K-Seal radiator leak, your only other choice would be a headgasket.
 
I'm OK with pulling the intake to fix the gasket. I'll double check the oil in a bit but I don't believe the HG was compromised.

Should I do a compression test to affirm this?

----Jer
 
Doing a Compression check would be your choice to do if you find out there wasn't a air pocket in the engine causing it to run hot.
 
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OK so I think I have a plan of action. I am 99.9% certain it is not a head gasket issue.

1. Drain collant
2. Change water pump
3. Replace lower intake gaskets

I'm reading the Chilton site on how to remove the upper and lower intakes. Are there any tips or tricks or things to watch out for? Thanks!

----Jer
 
OK so I think I have a plan of action. Since I am 99.9% certain it is not a head gasket, I am going to go ahead and change the water pump. While the water is out of I am going to go ahead and change the lower intake gasket(s) as well.

Is there any tips, tricks, or gotchas to removing the upper and lower intakes? Thanks!

----Jer
 
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