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Author Topic: CJ Overheating  (Read 241 times)

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Offline FLJager

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CJ Overheating
« on: September 18, 2017, 04:39:01 PM »
My new to me 82 CJ with a 258 is overheating. We recently replaced the original radiator because a previous owner must have patched a crack on the upper hose neck with JB Weld and it wasn't holding so well. After replacing the radiator, a short drive of only 2-3 kilometers and the coolant would start boiling over into the overflow bottle and we'd leave most of the coolant on the street, because it would overflow from the bottle.

We replaced the radiator cap with a new one, swapped out the thermostat and the water pump, all without any change in the symptoms.

An interesting thing though, with the radiator cap off, while the engine is running, if you pump the throttle a little, instead of the coolant level dropping, it gushes out after a moment. Normally, I'm accustomed to seeing the level drop a little.

So, we're thinking that the pump may be turning the wrong way. We've ordered a new one that turns in the opposite direction, to see if that helps but the impeller on the new pump turns in the same direction as the one it replaced. We're assuming that maybe it was the wrong pump to begin with, that maybe a previous owner had installed the wrong pump. The fan and pump turn clockwise but it appears by looking at the impeller that this is the wrong direction.

If a different water pump doesn't solve the problem, then we'll get a combustion gas tester, to see if there are combustion gases in the radiator, which may indicate a blown head gasket. We've not seen any white smoke coming out of the tail pipe, nor are we seeing any changes to the new coolant. Mind you, the coolant hasn't been staying in too long and we keep having to replace what ends up on the street. Also, when we filled the coolant system with a vacuum system, we didn't detect any symptoms that might have lead us to believe that there was a problem with head gasket or the block. A pressure tester at the radiator cap shows that the pressure gets up to 20psi within a few minutes and this pressure just pushes all of the coolant out of the system and into the overflow bottle, which then overflows onto the street.

So, suggestions, words of wisdom?
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96' Jeep Cherokee - Country
96' Jeep Grand Cherokee - Laredo
82' Jeep CJ-8

Offline cLAY

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Re: CJ Overheating
« Reply #1 on: September 22, 2017, 11:19:12 AM »
The water pump will always turn in the same direction no matter what pump you put it, unless you somewhow drastically change the belt routing.

What you are looking for is the sweep of the vane on the pump. If the pumps are different then the impellers should be mirror image.

From the quick research I just did a Vbelt engine should be counter clockwise and look like on the right and a serpentine belt engine is clockwise and looks like on the left. Note the "R" stamped into the impeller.


Do you have a t-stat with an air bleed hole and is it installed at 12 o'clock? The 258/4.0 is notoriously bad for getting air locks. I remove the heater hose line off of the front of the engine to allow air to escape while filling rad. When it starts to dribble out I fill whatever ever end didn't flow coolant till its full then jam the hose back on and finish filling. Sometimes having the front end raised helps too(up on ramps). A flushing T installed in the heater hose line makes it really easy.
Incompetence - When you earnestly believe you can compensate for a lack of skill by doubling your efforts, there's no end to what you can't do.
The only work I've done on a Rubi involved a chainsaw....

'93 ZJ, 5.2L, lifted/locked/36s..<gone>
'98 5.9e

Offline FLJager

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Re: CJ Overheating
« Reply #2 on: September 25, 2017, 12:37:13 PM »
Thank you cLAY, we'll look into the issue of air entrapment. When we refilled the system after changing the water pump, we used a vacuum fill system, which we assumed would reduce the chances of air remaining in the system.

We were looking again at information on the radiator that we purchased from Canadian Tire and we're concerned that it isn't large enough for the Jeep and that could be one of the primary reasons for it's overheating. The Spectra CU583 radiator that we installed has the same overall dimensions as the original but the manufacturer specifications show that it only has one row of tubes, where the original had two rows of tubes. This may also be why we weren't able to add as much coolant to the system, because the new radiator has a smaller volume than the original.

This is the radiator that we purchased from Canadian Tire:

http://ecat.spectrapremium.com/products/CU583

This is the radiator that we may get next week while we're in the US and then install next weekend:

http://www.omix-ada.com/replacement-radiator-81-86-jeep-cj-models-5045.html

So, here's what we have so far on possible causes for the overheating:
- air lock is preventing the coolant from flowing through the coolant system correctly
- the new radiator is too small
- ignition timing is incorrect
- there's a vacuum leak causing incorrect fuel mixture
- a failure of the head gasket is increasing heat and pressure in the coolant and thereby preventing it from cooling adequately

Of course, the problem could likely be a combination of the factors listed above.

------------------------------------------
96' Jeep Cherokee - Country
96' Jeep Grand Cherokee - Laredo
82' Jeep CJ-8

Offline Sixty4X4

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Re: CJ Overheating
« Reply #3 on: November 30, 2017, 09:02:46 PM »
Fan shroud on still??
2008 JKU Ruby, Jeep steel bumper, 9500 winch, 3.8L, 6spd, stocker