Why is our Jeep Overheating?

Posted by SpaceBuckChuck@reddit | askcarguys | View on Reddit | 33 comments

Hey everyone, we are at a loss and hoping some experts here can help us out. My oldest has a 2007 jeep grand cherokee laredo. A few weeks ago we found out the radiator was leaking. I filled it and drove it to my in laws to have my mechanic father in law to help replace it with a used but none leaking radiator. just as I arrived the engine completely stopped. We had a few sleepless nights worrying I might have warped the engine or cracked the block, but after rigorous checks and being able to turn the engine manually we found it all to be fine.

We replaced the radiator and everything seemed to check out. After about 5 miles on the road, engine goes from cool to overheating and engine cuts out. Towed it back, and replaced the thermostat. Still over heating, and realized it's possibly the water pump.

Replaced that and then once again everything seemed to be running incredibly well. Idle engine stays cool for 45ish minutes. I get behind the wheel, within 5 minutes the engine overheats and stalls out.

We're at our wits end and need the help from you all.

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itchybiscut9273@reddit

When you refilled it after the radiator change, you bumped the system to avoid air locking it right?

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SpaceBuckChuck@reddit (OP)

We are working to make sure we didn't leave air in the engine, will attempt raising the front and running it to hopefully dislodge any airbubbles

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itchybiscut9273@reddit

Just open the rad cap and turn it on. Let it run until it stops bubbling

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Miller335@reddit

You warped the head by overheating it and now it's leaking through the headgasket.

You need to run a leak down test and maybe get a boroscope down the spark plug holes to get eyes on the cylinders. Probably have a cylinder or two washed completely clean with coolant.

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Hash-82@reddit

Head may not be warped, but 99.99% the head gasket is leaking.
You could try retorquing head bolts.
Just run stage 3 torque value and pattern. Easy to try, and you don't lose anything but a little time if it doesn't work.
Good practice for pulling the valve cover if you have to yank the head.

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SpaceBuckChuck@reddit (OP)

With a warped head would it be able to drive for a short period then over heat? Or would it show signs right away, just asking clarifying questions.

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jrileyy229@reddit

Short period is not a defined unit of measure....

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SpaceBuckChuck@reddit (OP)

Fair point, about 5 minutes. Gauge would go from cool to in the red in moments.

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SpaceBuckChuck@reddit (OP)

We currently aren't seeing any other signs of coolant leaking (haven't been able to usea boroscope yet) but so far other fluids are all clear if coolant.

We are seeing signs that it's still leaking but haven't located that source yet. Father in law has laid out cardboard to see if we can track backwards where the coolant could be going.

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Hash-82@reddit

5 minutes? I'd say head gasket.
Leaking just enough on compression to displace coolant from the head. No other symptoms.
Head quickly overheats with no water in it.
I've seen it a million times... maybe... allegedly...

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mpython1701@reddit

Which engine?

Ran my 4.7 too hot. Thought i got stopped in time but the intake is a composite plastic and it warped/cracked.

Bad news is, no new replacement part. Have to upgrade to the 2008+ which can be expensive and time consuming.

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SpaceBuckChuck@reddit (OP)

It is a 4.7. Would that warp/cracked effect engine turn over? We can turn ii fine by hand and starts up like a dream. Only really overheats during regular driving for a few minutes/miles.

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mpython1701@reddit

Still ran but leaked near the back where heater hose attached. Assuming when you run, there is coolant loss.

Depending on severity, can also lead to vacuum leaks and running rough.

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Biobizlab@reddit

Back in the day when i had a grand Cherokee and it kept " overheating" it turned out being the thermostat. Mechanic said they go out often. Was a cheap and quick fix

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SpaceBuckChuck@reddit (OP)

Thought I replied to this but it vanished, we did install a new thermostat but are evaluating it to be sure we didn't wind up with a dud right out of the box.

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SpaceBuckChuck@reddit (OP)

We did replaced it but we're also entertaining the idea that we may have installed another bad thermostat.

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bcsublime@reddit

Who puts a used radiator in their vehicle what the fuck?

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Prudent_Situation_29@reddit

It's a Jeep.

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lunchbox651@reddit

Did you replace the radiator hoses with the radiator? A kink or collapsed hose will do it.

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SpaceBuckChuck@reddit (OP)

We are using the old hoses and bot the inlet and outlet hoses are in good shape with no kinks or bends. :/

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lunchbox651@reddit

Check they don't collapse under throttle? Don't know if it applies to modern cars but I had it happen with an older car of mine that the spring in the lower hose fell apart and while it looked normal when you gave it some throttle the hose flattened and the car would overheat.

Probably not your issue but just offering the idea on the chance it helps

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SpaceBuckChuck@reddit (OP)

We will for sure check this! While idling everything seems great but there could be collapsing during throttle for sure.

Any idea is worth looking into!

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Longjumping-Log1591@reddit

Did you put it on an incline to burp the baby?

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SpaceBuckChuck@reddit (OP)

Attempting to, maybe we don't have it inclined enough? How steep of an incline would you recommend?

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Left-Impress4056@reddit

Let me guess it runs rough in the morning for about 30 seconds.

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SpaceBuckChuck@reddit (OP)

When idling it can run for 45 minutes or more.

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SpaceCat72@reddit

Lol at oil and coolant look for loss. Pressure test the cooling system. Observe the exhaust. Look for whiteish smoke/vapor. You know water pump is good and radiator is flowing, also thermostat is good as well? New doesn't necessarily mean good. Test everything.

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SpaceBuckChuck@reddit (OP)

New thermostat but we plan to recheck this. So far exhaust looks clear. Spark plugs are next in the trouble shoot process.

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voucher420@reddit

You put in a used radiator that could be plugged or partially plugged. I would recommend checking it with a temp gun or one of those thermal cameras if you have one available. If you don’t, carefully feel around the radiator to see if it has any cold/cool spots. Not sure if you have an electric fan or a mechanical clutched fan, but I would recommend inspecting a mechanical fan once it’s warm to make sure you can’t spin it by hand (with the engine off). I would also ensure the electric fans are operating, if that’s what you got.

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SpaceBuckChuck@reddit (OP)

Its an electrical fan that appears to be moving freely and cooling as it should. I believe we have a temp gun we can use to check for cold spots. Thanks!

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