The overheating thread

[autotech98]

I know tony has done it that way.cant remmember what thread info is in though

[4.3LXJ]

Actually, we have different methods. His method, and I think this the thread for it, involves using the factory relay and choosing the correct wire. Mine, is to use a separate relay in which the output is spliced into the output on the factory relay. They would be parallel switches in which the rest of the circuitry is isolated from each other. But to each to his own. Both will work

[96greengoat]

So I just rebuilt a 94 engine to put in my 96/97 xj and I have been tackling an overheating issue since I put the engine in. It has a new radiator, new radiator cap, new plugs & wires, I polished the valves at work, new water pump, new thermostat installed correctly, I made a copper & brass coolant flush adapter & installed it on the correct heater hose, I purged the air from the head via the engine coolant gauge sender & i pressure tested the cooling system & it held pressure. STILL RUNNING HOT. It seems to heat up quicker than before. I also reset the pcm before u first ran the fresh engine.

I bought an ELM327 Bluetooth scan tool to troubleshoot without borrowing the scan tools from work. On a cold startup it seems to struggle sometimes (probably my old battery) and the scan tool says the spark advance is 17° at an idle. I tried to verify that with a timing light bit the water pump pulley is preventing me from seeing the timing marks past 15°. So I put the timing light on different plug wires to just observe the timing. HERES THE ODD PART: the timing mark did not stay in the same spot - when on plug 6 it jumped from 12, 13, 14, 15 then back to 12 and so on - the pick up coil is clear of rust & I did have to solder the wires on the CPS because the wires were damaged during the engine removal.
THE QUESTION IS: is my PCM acting up? I think I could have damaged it by running a larger wrangler alternator for a while before the rebuild (I had to grind the block & alt bracket to make it fit).
Please help! My initial thoughts was my distributer was off by a tooth on the cam but I want to make sure. It also has forgotten engine codes.

I mud. I crawl. I Jeep.

[4.3LXJ]

How is your fan clutch. You don't mention changing it. Fan shrouds? efan coming on?

[96greengoat]

Fan clutch is good, no shroud yet, still 30° outside when I work on it, efan will not come on - the coolant temp sensor at the thermostat has never read above 180 via scan tool - I have verified both senders with an infrared temp gun

I mud. I crawl. I Jeep.

[4.3LXJ]

So, it is running hot but the efan doesn't come on? Something is not right here I think or I just don't understand what the problem is

[96greengoat]

I checked the aux fan relay & it's good - something is definitely not right

I mud. I crawl. I Jeep.

[4.3LXJ]

First off, a fan shroud on the mechanical fan will increase its efficiency by quite a bit. I am guessing since it is not that good of a shroud, but say in the 30% range. The next thing to do is see if the number 85 or 86 pin on the fan relay is getting power and that the #30 pin has power

[96greengoat]

Agree on the shroud, the fan works when I turn on the AC

I mud. I crawl. I Jeep.

[4.3LXJ]

Then I would suggest your ECM is not turning it on. It is a fairly common problem. It will have to be replaced

[96greengoat]

That's what I was afraid of - is there any test to confirm the diagnosis?

I mud. I crawl. I Jeep.

[4.3LXJ]

When it is time for the efan to come on, there should be current to the 85 or 86 pin on the fan relay. If there is no current there, the switch inside the ECM is toast

[96greengoat]

Can I dip the coolant sensor in boiling water to test?

I mud. I crawl. I Jeep.

[slvmart]

There may be other systems like this available, but this might be a Painless solution (although not necessarily painless on the pocket book) :
Amazon.com: Painless 30102: Automotive@@AMEPARAM@@http://ecx.images-amazon.com/images/I/41Ur1eyg4IL.@@AMEPARAM@@41Ur1eyg4IL

[4.3LXJ]

I suppose that would work

[96greengoat]

I used a torch to heat up the thermostat housing to 217° (key in run) & the efan did not turn on, I checked & the relay did not have a good ground through terminal 85 (24 ohms between battery ground & connector terminal 85) which is supposed to be grounded through the pcm - I think 86 was always hot, when it should go to the switched power source, which I thought was odd. So I will check my PCM power & ground connections

I mud. I crawl. I Jeep.

[96greengoat]

When I grounded terminal 85 through a jumper the relay ticked on & the fan came to life

I mud. I crawl. I Jeep.

[96greengoat]

Just reset the PCM again & it came up with code 1391 - I've had my doubts about the timing chain so now I have all the reason I need to pull the timing cover & double check it

I mud. I crawl. I Jeep.

[96greengoat]

Chain is all good - I guess the only other thing it could be is the pcm

I mud. I crawl. I Jeep.

[Mudderoy]

So I just rebuilt a 94 engine to put in my 96/97 xj and I have been tackling an overheating issue since I put the engine in. It has a new radiator, new radiator cap, new plugs & wires, I polished the valves at work, new water pump, new thermostat installed correctly, I made a copper & brass coolant flush adapter & installed it on the correct heater hose, I purged the air from the head via the engine coolant gauge sender & i pressure tested the cooling system & it held pressure. STILL RUNNING HOT. It seems to heat up quicker than before. I also reset the pcm before u first ran the fresh engine.

I bought an ELM327 Bluetooth scan tool to troubleshoot without borrowing the scan tools from work. On a cold startup it seems to struggle sometimes (probably my old battery) and the scan tool says the spark advance is 17° at an idle. I tried to verify that with a timing light bit the water pump pulley is preventing me from seeing the timing marks past 15°. So I put the timing light on different plug wires to just observe the timing. HERES THE ODD PART: the timing mark did not stay in the same spot - when on plug 6 it jumped from 12, 13, 14, 15 then back to 12 and so on - the pick up coil is clear of rust & I did have to solder the wires on the CPS because the wires were damaged during the engine removal.
THE QUESTION IS: is my PCM acting up? I think I could have damaged it by running a larger wrangler alternator for a while before the rebuild (I had to grind the block & alt bracket to make it fit).
Please help! My initial thoughts was my distributer was off by a tooth on the cam but I want to make sure. It also has forgotten engine codes.

I mud. I crawl. I Jeep.

When Matt stabbed the distributor in my 98, he messed and messed with it to make sure it wasn't a tooth off. I wonder if your distributor is installed correctly.

[Mudderoy]

Chain is all good - I guess the only other thing it could be is the pcm

I mud. I crawl. I Jeep.

http://www.cherokeeforum.com/f2/rough-idle-code-p1391-124396/


Well for anyone that is interested. I replaced the crankshaft position sensor. The CPS I took out was a masterpro from oreillys. I went to napa and bought a echlin CPS. Cleared all my problems up and running great now.

[96greengoat]

I'm getting a non-autozone engine temp sending unit after seeing so many issues with them on other forums

[blazer2]

I went with one from Oriley Borg Warner was the brand.

[96greengoat]

I went with a crown part - if it acts up I'll get either Mopar or O'Reillys & if that doesn't work then maybe off with the head to get magnafluxed, I don't know. I did the valves at work on my own free time with the help of my very experienced co-workers & we saw no signs of a crack or warp during the whole 2 weeks it was at the shop

[96greengoat]

But once it stays above freezing around NW Ohio I am going to flush the snot out of the block to make SURE there's no air or debris in the cooling system

[96greengoat]

When Matt stabbed the distributor in my 98, he messed and messed with it to make sure it wasn't a tooth off. I wonder if your distributor is installed correctly.
I remember that episode - he changed it by 1 tooth on the cam. It seems like there should have been a P0016 code from the CKP & CMP changing 15° relative to each other

[96greengoat]

I remember that episode - he changed it by 1 tooth on the cam. It seems like there should have been a P0016 code from the CKP & CMP changing 15° relative to each other
That was the crane-cam-valve-drop-piston-eating-engine :) good memories!
I made it so when No. 1 was tdc or just past it the rotor was pointed at cylinder no. 1 - I would certainly feel better if i could get someone like you or Matt to come out & check my work once in a while

[blazer2]

But once it stays above freezing around NW Ohio I am going to flush the snot out of the block to make SURE there's no air or debris in the cooling system
So you are doing it on Saturday because the weather man says it's going to de in the 50's:rolleye0012:

[96greengoat]

Sunday - unless there's freezing in the forecast

[blazer2]

Should be nice Sunday no snow :bang:
I haven't looked at weather underground for the weekend.

[96greengoat]

Crown part works perfectly! Now I noticed the oil pressure gauge is low & i think I hear l some lifter noise - I'm going to check pressure with a mechanical gauge

[tacklebox]

Summer sucks. I'm dealing with the same temp creep at speed Tony. I can run all day, AC blasting under 60 mph. Even 65. Break 70-75 and she creeps up to 220-225. Holds steady there but still I don't like it. Maybe touches 230 if I rag on it. Never breaks 210 under any other conditions.

Only thing I haven't personally replaced is water pump and rad BUT both are supposed to be less than 2 yrs old and visually look new. System has been flushed. Twice just to be sure. Never flushed anything nasty out. Just clean coolant.

Grrrrrrr

102 amb today. I ran the first 30 mi home AC off at 75mph she held about 215 then ran the second 30 mi at 65 mph temp stayed ABOUT the same.

I have verified temps with IR gun
Today I ran my OB app to watch temp as well. Was damn close to the gauge.

Hmmmm can't decide what next.
Prob test coolant for exhaust gasses before firing parts canon.

[bluedragon436]

Yeah I'm fighting with mine creeping, especially when it is extremely warm out.. and even more so if I'm sitting in traffic or anything like that... If it's not too hot out, like 85 down... it usually does alright.... I know the water pump & rad are brand new and good, cause I replace them after the first summer I had it and saw the temps.. it certainly has helped, but only to allow me to get into warmer outside temps, before she starts creeping... I've done a flush and never had anything nasty looking either.. but will say I know one clog issues that I have is the heater core.... Might have to try and flush/backflush it again soon, and see if that helps any.. Any other time I've ever done the flush/backflush on the heater core was right before the winter so that I'd have some semblance of heat...

[gary63]

you may have to get the air out of the engin bay so more air can go though the rad we put port holes in the fenders of one guys it helped . a nother did revers air scoops to the back of the hood . the air would go down the fire wall making a vaccu to pull more air in.