I think I have an Over Heating Problem

[Green Mesa XJ]

Cap on the res just sits there.

How did y’all set the timing? Looking at the 3.4 timing cover it’s just a sensor, no markings.


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[AMC86Kid]

i never messed with the timing chain just installed the engine with it the way it was 

the weird part is i only get the problem when the engine gets up in temp 

it dosent do it when its cooler 

[Green Mesa XJ]

I don’t think it’s temperature related per say any more than it is when the viscosity changes and the carburetor drop the rpm.

I’m not ever sure you’re overheating or running hot. The radiator seems in the right range, the IR scan on the top of the motor might or might not be the correct way to get a reading.


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[Green Mesa XJ]

I’d did some reading on gettin a IR temperature on the engine most suggest upper radiator near the thermostat housing, black surfaces for more accurate readings.


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[AMC86Kid]

i was scanning around there but my motor does not have any black surface 

[Minuit]

Try the upper hose. The upper hose temp should be roughly equal to the coolant passing through it.

[AMC86Kid]

sounds good i will check the upper hose temp next time i run it 

but now if only i could figure out whats causing that weird noise at the end of the video 

 

https://comancheclub.com/forums/topic/53998-34-ltr-engine-stalling/

[AMC86Kid]

ok so now that i got the engine back up and running

i am gonna look up the timing chain info and see if that has anything to do with my overheating issue 

[Green Mesa XJ]

Well overheating could also be the fuel mixture too lean, which is possible, but wouldn’t be a first guess.

 

I’m not 100% on the water pump and rotation be correct but if your and this is a jeep you plan to hold on to I’d buy a new radiator, I don’t know what else could fit it, maybe a lot it is a pretty classic size and space .

 

 

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[AMC86Kid]

so apparently the timing chain can only go on one way correctly and thats it 

the guys that rebuilt the engine must have put it on the right way 

and i really doubt that it jumped a tooth by now 

 

well I'm pretty much all out of ideas 

maybe i can pressure check the radiator do you know if places like autozone do that for free?

also is there any way to run my ignition coil with out a computer ?

[Green Mesa XJ]

The timing chain can go a lot of ways since it runs they set it correctly.



Timing is how the engine fires the spark plug in time with the compression stroke.
The timing cover has marks on it, when under a strobe light timing gun set to the first cylinder ignition will light up the mark on the harmonic balancer, line it up by moving the distributor a to advance or retard the timing. The timing is set by lining the marks up to what the factory specified.
Rpm and vacuum have to be exactly right. 2.8 I believe is 700 rpm with vacuum advance unplug from distributor and vacuum line block so it doesn’t leak.
Electronic control ignition usually have a way to trigger the correct rpm by bridging two contact points in the wiring or plugging something to a plug in the wiring harness.
This may be a poor explanation, this link might explain it better
https://www.yourmechanic.com/article/how-to-find-an-engine-s-top-dead-center-by-ed-ruelas

Missed timed the engine will be igniting at the wrong point in the compression stroke, with exhaust and intake valves in the wrong position.

You need to find out what you have of the 86 California wiring and computer. If it’s running I suspect you might have is all intact, or maybe the PO rewired it. Ether way you need to figure out what you’ve got.
You computer should be a shiny silver box under the dash, or in the engine bay. Since it’s a 86 I’d bet if you follow the harness there’s a big oval rubber plug the wires go through the firewall almost exactly behind the engine, this should lead to the computer if you have it. But I’m not 100% certain, it’s the location on my harness that has timer for a emissions maintenance reminder light since federal emission have no computer.


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[AMC86Kid]

yes it does appear that the wires lead to the computer under the dash 

i will play around with it and see if there is a way to bypass it 

for now I'm trying to figure out whats causing my overheating issue 

[Green Mesa XJ]

Radiator would be my guess. If all else is correct. I’ve only known radiator shops to test radiators, Vato zone might have pressure testers to pressurize the system to look for leaks. You need smithing like flow test??, I forget the correct term, been years since I sent one off.

Just confirm the wires go to the computer and it’s all intact. At this point I’m not sure where to go with that. Simple is vacuum advance with no computer and that carb, but I’m not sure about the wiring. Since it runs the computer is probably working, not having the plugs on the carburetor take the computer screwing up the mixture and engine speed out of the picture.

I would leave timing alone as well since the 95 3.4 does not have the timing marks the 2.8 used. You may have to adjust it later or replace it with a vacuum advance distributor.


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[AMC86Kid]

i don't think its the radiator because when i squeeze the upper hose i can feel the flow of coolant moving pretty good 

and pressure testing the radiator only checks for leaks in it and i do not see any coolant leaking out of it at all 

so i called a local mechanic and he thinks that the head gaskets were not installed properly

and that i should do the test with the liquid on the radiator cap to see what color it changes to 

you know what I'm talking about ?

 

 

[Green Mesa XJ]

Compression test, easy to diy. Plenty of videos on how to. This will give you an idea of the health of the engine .

I’ve done the headgaskets on the 2.8 I’m rebuilding it’s not rocket surgery. Not to many ways to screw them up unless the block or heads are warped. Or they didnt torque to spec. After its install it’s overheating to 280 range that kills them. But I only know what’s online I can tell what actually happening .

If the radiator does not have enough flow, or air through the coils, it runs hot. Same if the water pump is dying.
Your reservoir tank wasn’t moving either with the expansion of the fluid so something is wrong there maybe then rad cap.




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[Green Mesa XJ]

Bye Test your talking about might tell you something but only if the BHG is bad enough to send enough exhaust bubbles through the radiator to change the color of the Test liquid

 

 

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[AMC86Kid]

if the head gaskets don't leak then the radiator might have poor flow threw it due to clogged vents 

so I'm kinda hoping that the combustion gas test tells me that there is no gases in my coolant then 

i will simply change my radiator and see if that makes a difference

hope this works ...

[Green Mesa XJ]

Compression test will tell you a lot. If the gasket has blown out, if valves or piston rings are bad you’ll have low compression on one cylinder or two neighboring cylinders in the case of BHG.
The gas Test will work if the problem is bad enough. So far every car ive tested in the last four years has past the Test, I’m curious about how accurate it is on a real BHG.


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[AMC86Kid]

i think combustion leak test is the better choice for my scenario because 

i have no smoke coming out of my tail pipe if coolant was getting in the smoke would burn up and get pushed out 

i tried testing it but my battery needs to be charged so I'm gonna charge it over night and test it tomorrow morning 

i really hope i figure this out so i can get the rest of the truck done 

[Green Mesa XJ]

????
Combustion leak test tells you very little compared to compression testing. Leakdown testing tells you a whole lot more but is a harder test to do.

And combustion leak test has to have a big enough exchange of coolant to exhaust to show up. If it’s a sleeping head gasket leak it’ll probably never react.
Are you losing coolant?

Overheating is a symptom of BHG because it is taking enough coolant out of the engine and burning it up replacing it with pockets of exhaust. When running a car with BHG it’s those pockets of air which cause temperature spikes.
Running too hot is more a symptom of: radiator, air flow through the fins of radiator, water pump, thermostat, clogged water ports in the engine. Which will cause a BHG.
The condenser in front of the radiator can cause problems, detritus caught between rad and condenser, condenser clogged fins and blocking air flow.

You need to get the reservoir working too. May just be the 18lbs rad cap, I think oem was 13 lbs. but the reservoir should show some kind of change as the engine heats and cools.









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[AMC86Kid]

i had done the leak test and it did not turn yellow i let some coolant out to not get any in the test tube 

but the pressure went up as i ran up the rpms and it flowed in the test tube so i dumped the liquid out and retested it 

i must have pumped at least a hundred times and all i could get was a teal color i could not get green or yellow so i don't think my head gasket is blown 

i think either my radiator is bad or my water pump is not pumping with enough pressure 

do you know how much pressure there should be with the engine running with no thermostat 

 

[Green Mesa XJ]

Thermostat missing could cause over heat too. But I doubt it in this

Radiator part # 53000521 , it’s crown part now but looks oem,
Core listed as 16.75 wide, 20.250 high.
the stuff rockauto is selling I don’t like because of the plastic tanks. When I bought my last radiator for it they were common aftermarket, now it a bunch of Chinese knockoffs.

It looks so much like a old cJ or YJ radiator I wouldn’t be surprised if a aluminum 3 or 4 core for a wrangler would work.

Water pump, if you don’t know what it’s running or how new it is I would replace it just on principle.
I’m Not sure if there’s a recommended brand on these pumps, I’ve just used whatever was at the local parts house for the 2.8. The Camaro is 3.4 93-95 only on these pumps.


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[ParadiseMJ]

Two things about the overheat problem:

No t-stat WILL first look like its' running cooler and then overheat.  A 180 t-stat will not lower or control the operating temp.  The t-stat spec only controls the minimum temp at which it opens, it does not close at any max temp.

 

If the radiator is original, it's most likely the radiator, in my experience.  Coolant can flow right through a bad radiator and the tubes can still be clogged/inefficient.

[AMC86Kid]

i agree i think it is the radiator i got a new one and I'm in the process of putting it on 

anyways wile i took the old one off i noticed that the fluid had rust residue in it 

and the upper flex hose coils inside the hose were rusted to 

maybe rust spread from the old radiator to the flex hose coils and made the corrosion even worse 

then the radiator was never able to get rid of the heat so now I'm gonna 

replace the radiator and replace my hose and flush out the engine 

i want to make sure i don't clog up my new radiator and its set up 

[AMC86Kid]

ok so i put on the new radiator and flushed out all the old fluid then filled it up with new fluid and it ran on idle 

for about 45 minutes and stayed below 200 degrees then i stared running it at around 3,000 to 4,000 rpm

and after 10 minutes she starts to get up to the 230 - 240 temp 

so basically i got it to stay cool at idle speed but i can't get it to stay cool when you run the engine with speed

 

any ideas on what i should do now ?

is it possible to take the water pump apart and look at it or do i need new gaskets to do that ?

and any ideas on how a good water pump should look or how much pressure it should push?

i had it running with no thermostat i will test it again with a thermostat tomorrow 

also am i suppose to have a lot of pressure in my radiator hoses once it gets up in temp?

 

also the 3.4 has a 18lb Rad cap and the 2.8 has a 13lb Rad cap does it make a difference which one i use ?