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4.0L jeep overheating


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swhitney
New User

Sep 13, 2009, 8:37 AM

Post #1 of 8 (6750 views)
4.0L jeep overheating Sign In

1999 Jeep Wrangler 4.0L I6. Engine overheats under heavy load or over 45 MPH. Radiator replaced due to leak / Cooling system had excessive rust, so much so that the fins on the waterpump were gone when pump was removed / Replaced waterpump with reverse rotation pump (serpentine belt) and replaced thermostat with 160 deg / Thoroughly flushed system with non-acidic flush and removed waterpump to verify block looks like new inside / All coolant hoses changed because they felt brittle / Attempted reverse compression test by applying air to each cylinder on top dead center and found no bubbles in radiator cap or air leaks from throttle body or exhaust / Air conditioning condenser free of debris and nothing between the condenser and radiator to block air flow / Fan clutch replaced just for good measure.

Did I miss anything?

Thanks,


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Sep 13, 2009, 10:38 AM

Post #2 of 8 (6740 views)
Re: 4.0L jeep overheating Sign In

Although pumping air into the cylinder sounds foolproof, it really isn't. The best way to test for that is with an emissions analyzer over the radiator.

I'd also remove the upper radiator hose and run the engine just to make sure the pump is working properly and your getting good flow.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



swhitney
New User

Sep 13, 2009, 10:54 AM

Post #3 of 8 (6736 views)
Re: 4.0L jeep overheating Sign In

What's the best way to increase flow?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Sep 13, 2009, 10:56 AM

Post #4 of 8 (6733 views)
Re: 4.0L jeep overheating Sign In

You can't increase flow. You just verifying that you have the right pump rotation.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



swhitney
New User

Sep 13, 2009, 12:13 PM

Post #5 of 8 (6729 views)
Re: 4.0L jeep overheating Sign In

I have verified that the coolant is flowing and in the correct direction.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Sep 13, 2009, 4:57 PM

Post #6 of 8 (6722 views)
Re: 4.0L jeep overheating Sign In

?? What's this with the reverse water pump?? If fins aren't right flow would be too low if directional,

T



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Sep 13, 2009, 5:03 PM

Post #7 of 8 (6717 views)
Re: 4.0L jeep overheating Sign In

Jeeps use 2 different water pumps depending on what kind of belt they use because the pump that is driven by the backside of a serp belt turns the opposite direction and they make them both ways.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Sep 13, 2009, 5:43 PM

Post #8 of 8 (6713 views)
Re: 4.0L jeep overheating Sign In

Learn something new every day! I didn't know how they did what with an age old engine TMK?? Unfortunately forget two or more of something every day too - just laugh. The alternative is too sad,

T







 
 
 






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