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86 Cherokee overheating problem

Good evening, I have a 1986 Jeep Cherokee Pioneer with a 2.46L 4-150 engine with an overheating problem. I just purchased it as a basket case and am trying to get it back on the road again. I found that there were two bad valves in the number two cylinder. The intake valve was burned through with a large grove across the face. The exhaust valve had gotten so hot that it had Cupped and sat too low in the seat. The head had a complete professional valve job and was shaved slightly to ensure it was not warped. After it was installed the engine ran rich and I found a hose was disconnected from the Mapp sensor. I also found that someone had installed the wrong O2 sensor and it was replaced with the correct one. The radiator has been flushed a couple of times and now seems clean. There is a slight leak in the radiator between the converter and muffler. It seems to idle fine but has a sluggish pickup in engine RPM. Also backfires once in a while and wants to get hot climbing even a small hill. Timing seems to be slightly higher than

12 BTDC. Have not checked the fuel filter as of yet. I cannot seem to find any information as to the correct hose connections that had to be removed when doing the valve job. All seem to be correct but cannot tell for sure. Can you advise any other areas to check and perhaps point me to a site where the hose diagram might be found? Thanks Don Smith
Reply to
Don Smith
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Take a good look at your radiator. The one on my 89 Cherokee 4.0L was rotted real bad. A new one with more rows of tubes was like $135 at a local parts store. Yours, if original, most likely has one row being a four cylinder. Also could be the fan clutch if it has one.

JoBo

Reply to
Jo Bo

I am thinking fan clutch as well on something that age.

If it is hot and you shut it down, the fan should stop almost instantly. If it keeps on spinning, the clutch is done.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Jo Bo wrote:

Reply to
Mike Romain

Reply to
Don Smith

The fan clutch should be 'radically' different when hot and cold. Really radically!

Cold it is supposed to free wheel, hot it locks up and stops instantly when shut down.

If it acts the same, it is toast.

Mike

D>

Reply to
Mike Romain

You're giving a pretty fair description of a plugged radiator or a collapsed lower hose - can't pull water out as fast as it goes in. I looked at the Commanche manual for the 86 and can't tell - did the

4-banger have that w> Thank you JoBo and Mike for your input. Still working on the problem of
Reply to
Will Honea

All seem to be correct but cannot tell for sure.

If you've been working on the cooling system, did you put everything back the way it was? If you get the two bypass hoses switched, you'll get boiling, no heat in cab etc. Check that the smaller ('out') hose from the thermo housing goes direct to the heater core with a T to the TOP of the expansion tank. Check that the bypass hose ('return') from the block (the one attatched to the long metal tube to the left of the thermo housing) goes to the heater core with a T from the BOTTOM of the expansion tank. I got the mixed on my '87 and caused all sorts of grief, mischief , expense and puzzlement. If backwards, the system will draw in air from the top of the tank, and that will give you the symptoms of a BHG, clogged rad, bad pump , you name it. I wish I didn't have to have learned this the hard way.

Reply to
master of none

Thanks all for your inputs. Mike the fan clutch does not become real stiff after the engine has been run for awhile. It does seem to have some resistance in its action both cold and while somewhat warm. Will try to get it hot and recheck. Thanks for the tip.

Hi Will. I think I agree with the diagnosis of a plugged radiator. While it looks clean without any rust I think I will remove it and check it out. The hose at the bottom is new. The volume of water at the top of the radiator seems to show that the pump is working fine. Might be some crap that has lodged in the bottom tank of the radiator. It is a single row radiator. Does the radiator out of a 84 V-6 fit? If so I might be able to try a two row radiator. Thanks to you also, for your suggestions.

Hi Master of None. What I had done was a head removal and valve job. Two Valves were bad from overheating and there was a bit of head warpage. All of that is fine now but I could tell that there was a problem before that caused the overheating. The vave job and repair did not correct it. None of the other hoses were removed that were not required to get the head off. Most of the water hoses were easy to locate their proper connections. The vacuum lines and vapor recovery (Fuel Injection) small hoses might not be connected correctly. Cannot find the diagram for the system to verify. None of my water hoses seem to have a "T" connection. The smaller of the hoses that connect to the thermostat housing loops over to the intake manifold. There is a heater hose connected to the top area of the water pump that goes to the heater core area of the firewall. It is about the same diameter as the one that comes off the thermostat housing. However they are not long enough to be switched. Thanks for all of your help also.

Also I was not sure about the engine might be running real lean or with advanced timing. Since I am also experiencing sluggish pickup during the low end of the Rpm's as well as a bogging down during the higher end of a Rpm windup, I was also wondering about bad sensors or even a partly clogged fuel filter. Don

Reply to
Don Smith

I think I have repaired the overheating problem at last. I removed the radiator to change it over to a two row unit and found that the area between the A/C radiator and engine radiator was almost completely clogged up with dirt and leaves. I went ahead and changed the radiator but the old one looks good now that it can breathe. Ran the vehicle up a couple of hills and the temperature stayed down where it should. Thank you everybody for your help. Don Smith

Reply to
Don Smith

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