3.4 Ltr Engine Stalling

[AMC86Kid]

Ok so here it is guys the video i said i was gonna post:

https://streamable.com/do0sb

 

for some reason after i run the engine for about 20 minutes 

it gets up to its operational temperature which looks to be around 200 - 220 degrees

then the motor slows down weirdly and my father turned it off

cause we were not liking what it sounded like and didn't want to mess anything else up until we can figure out whats going on 

you guys have any ideas and feel free to ask me any questions that your unsure of 

i think the video helps explain my problem a lot 

[Green Mesa XJ]

I’m not sure about that noise. To me it sounds like if top end valve train related.
But I’ll let others more versed in these things make a more definitive diagnosis.

About the timing, you said you didn’t touch the chain, which is fine no reason to is it was replaced. I’m curious who set the timing and how. That engine didn’t have a distributor originally somebody put it in there and set it. It maybe perfectly correct or it may be off. Since it runs it can’t be too far off.


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[AMC86Kid]

i think the distributer was already on the motor when i got it 

[Green Mesa XJ]

Hum, then they set the timing to something close but as you tune it you may have to move the distributor but you’ve got no timing marks to check it with. Guess leave it alone unless you have to touch it.

 

That noise I’m hoping somebody will chime in on it. To me it sounds like there is something lose in the top end: rockers, push rods, lifters, something like that.

I’d pull the valve covers to double check if you haven’t already.

Setting the valve lash is a PITA on this motor. Not rocket surgery just repetitive process to get it set.

This thread has some good instructions, a few good videos if you search for them

 

https://www.thirdgen.org/forums/v6/165647-valve-adjustment-2-8l.html

 

Anyway that my guess for the sound if it’s not and it’s not oil flow related then it’s pretty much SOL start pulling the motor apart time.

 

 

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[AMC86Kid]

ok so i tested it again  this morning and same results 

it starts up and runs fine when its cold 

then after 25 minutes of running it gets up to 210 - 225 degrees 

and i let it run on its own until it died by itself 

here the new video:

https://streamable.com/xlb1b

 

I then went one step further and tried to start it back up after it died on its own

but had no luck so i let it sit and cool off check out the bonus video

https://streamable.com/io54w

 

any ideas guys, man i sure hope i figure out whats going on so i can finish the rest of the truck

 

[Green Mesa XJ]

Does it smell like gas? What does the oil look like?
One thought was a cylinder not firing and filling up with fuel. Or bad ignition coil.

But the engine slows down as it gets to operating temp so it could be the carburetor still.

Take the temp on the top hose right before the metal of the thermostat housing, meaning back a little from the clamp so you’ll get a accurate coolant temp as possible with just the hose and coolant and no metal.



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[Green Mesa XJ]

Oh I forgot you’re not running the alternator right now, it could be 20 min is the limit for the battery, dunno


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[AMC86Kid]

no its not the battery 

i think it might have to do with ignition coils electrical wiring 

i have a new ignition coil but the wiring may loose its signal when it gets up in temp 

i have to look up how it works and how is it wired maybe i can run new wires away from the heat and see how it performs 

 

 

uk so the one wire to the left goes to the distributer 

but where do the wires on the 4 prongs to the right go 

one must be 12 volts and one must be ground but what are the other two prongs for ??

[zomeizter]

Ensure that you're not losing fuel supply due to vapor lock cause by heat near fuel lines...

[AMC86Kid]

i have and the fuel is constantly pumping to the carb so i don't think its the fuel 

 

does anyone have like a wire diagram or a pin layout for the ignition coil

I'm trying to figure out how its wired to work i feel like the heat is giving me an electrical issue 

[Green Mesa XJ]

I have the electric diagram but I’m not going to be home until the weekend.
It’s a standard gm ignition, ought to be layouts for it around.
If yours is like my federal emission 2.8 you have a four prong (total number) module in the distributor that controls spark, California emission and later models have a module with more prongs for wires to plug into to it and go to a computer.
Your Distributor should have vacuum advance as well.

Looks about like this


Two wires go to the module from pick up coil, little thing that looks like a stargate inside the distributor. It sends the signals on where the engine is to the module, module sends the ignition coil to spark via two wires from the module to the coil. You can isolate that plug easily enough and trace it back to the distributor I suppose any repair manual dealing with the 2.8 will have procedures on how to test it. The other two wires on the other ignition coil plug one is the power source and should feel like a heavier gauge wire, the other wire I can’t remember what else it does but also feeds the tachometer signal. At least this is how I remember it, been years since I had to mess with fixing those plugs.

(Edit: Found a test for the gm coil
http://easyautodiagnostics.com/gm/2.8L/ignition-coil-tests-1 )


Re: the noise the makes as it stalls out...have you doubled check the rocker arms, push rods and lifters are all correct?

Distant possibility but could be stalling and making noise because the distributor is wayyyy off, when the rpm and vacuum advance change it can’t cope.
Someone that has worked with these older engines more might have better ideas.





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[AMC86Kid]

thanks i will read the stuff in the link and see of what i can make of it 

but just like the pic in the link i have a ignition coil separate from my distributer 

this is my ignition coil:

http://www.rockauto.com/en/moreinfo.php?pk=6399675&cc=1181393&jsn=386

distributer: 

http://www.rockauto.com/en/moreinfo.php?pk=6283911&cc=1181393&jsn=380

[Green Mesa XJ]

Ok there’s part of your problem. Maybe.
That distributor should have another input to control it, the federal emissions 2.8 had vacuum advance. What the hell is that jeep wired for.
Do you have plugs that go to it? A computer? Looking like a California emissions jeep if it has all that. Which might makes sense why the PO thought the crappy federal emissions carburetor was a upgrade.

Ignition coil looks correct and was standard gm for many years.


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[AMC86Kid]

yes the jeep did come from California i looked it up 

does that mean i have a more complex system?

[carnuck]

That distributor with the extra wire is spark timing controlled along with EFI. Depending on your carb/ ignition requirements, this one from an '80 Chevy Citation with 2.8L is simple as they come. I ran mine with an aftermarket carb and the cap and rotor from a '77 Nova with 250 inline 6 motor and external coil but we weren't doing a Jeep MJ or XJ with it so I'm not sure about firewall clearance. (Postal Jeep had more room)

 

 

https://www.rockauto.com/en/catalog/chevrolet,1980,citation,2.8l+173cid+v6,1040421,ignition,distributor,7108

[Green Mesa XJ]

Well actually they had a more complex carb and computer trying to adjust it. Efi or tbi would have been a upgrade.
God I’m not sure what’s the best thing to do, assuming you don’t have the computer you’re going to need to change some crap over to the federal. Unless you can’t not sure what the law is where you live. Down here it’s the Wild West, well Wild South with no emissions testing.


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[AMC86Kid]

I'm pretty sure we have just regular federal emissions here in AZ 

 

anyways i changed the area that my ground was connected to 

 

it was hooked up to this bolt on the exhaust

 

 

so i switched it to the firewall 

 

and i was able to get the engine to run for 45 minutes and it did not die

but i noticed that i now have a small oil leak, i will let it cool off and try to find it tomorrow when its cold 

also i checked the temp and at idle she stays around 215 - 220 but then i pushed the gas and tried to see if the temp would go up 

as the RPM go up and yes the temp was heading up to 230 - 240 so i turned it off 

 

looks like I'm back to an over heating issue 

I'm pretty sure i shouldn't be getting over 220 what do you guys think 

[Green Mesa XJ]

Ah, these motors like to leak a little oil. Be good to find where it’s leaking but I wouldn’t worry about too much.
If that the temp off the top radiator hose it’s too hot. Either the water pump/rotation is still incorrect, or the radiator is the trouble.

Would that engine and that distributor even run with out the computer?

I know the vacuum advance receives the impulses to fire from inside the distributor.


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[zomeizter]

28 minutes ago, Green Mesa XJ said:

Ah, these motors like to leak a little oil. Be good to find where it’s leaking but I wouldn’t worry about too much.
If that the temp off the top radiator hose it’s too hot. Either the water pump/rotation is still incorrect, or the radiator is the trouble.

Would that engine and that distributor even run with out the computer?

I know the vacuum advance receives the impulses to fire from inside the distributor.


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Leaks seem inevitable from the valve covers, at least that is the case with my POS 2.8L.

Is there a fan clutch on the water pump? If so, it may have seen better days and causing the overheating issue, check it out.

 

Say Green, the vacuum advance receives no impulses and does not fire, maybe you meant to say ignition module?

[Green Mesa XJ]

Sorry, I’m confusing some of the terms, there’s s pickup coil inside the distributor that sends the impulse to the ignition control module, the ICM send a signal to the ignition coil.

What I’m not sure about is how the non vacuum advance distributor works,
does it have the same set up without the vacuum advance hardware?
if it does then the engine can run without the computer but it will not run right because it will not advance the timing correctly.

If he’s got the computer it is no big deal to keep it like it is, if the computer is gone or doesn’t work then. Some kind of conversion to vacuum advance will be necessary.




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[AMC86Kid]

i believe that the ignition coil does have some wires that go to the computer but i will have to double check 

 

i will look for the oil leak today and look up the timing chain see how thats suppose to work 

 

also since were back to an over heating problem i will have to go back to my over heating post 

 

[86FUBAR]

So first off did you ever get anywhere with the carb adjustments? I never herd anything else after the last post in your " carb" thread ? Also does it have the correct thermostat in it ? And correct I mean one for a 2.8 ?  Everything you get for it other than some internal pieces and stuff pertaining to the serpentine belt setup etc. should be fo the 2.8. Perhaps replace the t-stat anyway as they are cheap as the temp seems way to high to me . What's the oil look like ? Could be thinking out when it gets that hot causing a lifter to collapse maby . And when is the electric fan kicking on ? Could be set to late and that can cause it to just run higher temps all together. ( had that happen to me before)

I noticed in some other pics that the ported vacuum switch on the manifold had been bypassed, the carb might need the vacuum inputs to better adjust itself.

[AMC86Kid]

86FUBAR

yes i managed to get the carb to work 

i also put in a new thermostat its a 180 

i put the fan on a manual switch so i turn it on when i want it on 

if you have anymore questions go to the lastest post and ask right here:

https://comancheclub.com/forums/topic/53984-i-think-i-have-an-over-heating-problem/