I think I have an Over Heating Problem

[gogmorgo]

When the engine is under load, usually there's much more air moving through the radiator. Cause you're driving.

if it gets hot while you're driving it then maybe there's an issue but I'd say it's probably okay. 

What makes you think there's a lot of pressure in the hoses? Generally, yeah, things expand as they warm up...

[AMC86Kid]

well i had the fan on the motor side sucking in air and moving it towards the engine

and i had a regular ac fan that i put in front of the radiator on full speed 

so i was simulating that the vehicle was moving and it got up in temp to fast 

 

as for the pressure i turned it off and then the reservoir level went up so i had more then 18 lbs of pressure in my radiator 

thats kind of a lot don't you think shouldn't i always be below 18 lbs 

[Green Mesa XJ]

Well you’re using 2.8 cooling system. I’d assume you’d need the appropriate cap, however people use different pressure adjust the boiling point. Does the reservoir expansion tank work?

If you pull the water pump you’ll need a new gasket, they are paper with a little rtv so they tear when pulled.
If you do replace the pump I’d run the belt like the Camaro does just to be 100% sure it’s spinning the correct way.


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[AMC86Kid]

how do i know it the reservoir expansion tank is working?

[Green Mesa XJ]

how do i know it the reservoir expansion tank is working?

The volume of coolant will expand as the engine gets hotter. If volume is not changing during operation something blocking the line.

 

 

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[AMC86Kid]

yes the pressure under the Rad cap does build up so the volume is increasing i noticed this as i ran it a little with the cap off 

but the fluid level in the reservoir only goes up i havent noticed it goes down but i will double check on it tomorrow 

 

but that shouldn't cause an over heating problem does it ?

[AMC86Kid]

Good new i figured out what my problem is 

the bad news its a bad head gasket 

the combustion test passes when the vehicle is idling 

but when you run it with RPMs then the blue liquid turns yellow 

so it only leaks when under pressure (i guess i learned something)

that must be why my rad hoses have so much pressure in them when i squeeze them 

 

 

now i guess I'm going to learn how mush money this will cost to fix

I'm gonna have to pay someone else to change them i don't have enough experience to know that I'm gonna do it correctly 

[Ωhm]

Those bubbles should have showed up in your coolant recovery bottle. Two (2) types of radiator caps our available out there and I, truthfully, don't have a good understanding of either one. I just know, one of them is for a coolant recovery system and the other one isn't. This difference is based on how they work, not on PSI rating. Investigate your radiator cap. Do you have a part number for your rad cap?

[AMC86Kid]

here is my Rad cap info 

http://www.rockauto.com/en/moreinfo.php?pk=48507&cc=1251931&jsn=396

i think because its an 18 lb cap it was able to hold most of the pressure and i noticed that the reservoir only goes up and not down 

but i will put a new 13 lb cap on it after the head gaskets get changed 

[Green Mesa XJ]

I thought you had said it only went down which would make me suspect a coolant leak. Guess it doesn’t matter now

 

You could try retorqueing the head bolts but at this point it’s probably truly blown.

Did you hit extreme temperatures? Did you suspect the rebuild?

You always thought you had a heat problem from the beginning just wondering why.

 

What you can do is pull the head and put a new gasket in after cleaning it up. By the book is take it to the machine shop but these iron heads don’t warp too bad if you didn’t cook it hard, you can usually do a few thing to check if it’s warped clean it up a slap a HD extrem duty headgasket on it.

I’d do a compression test to see which cylinder head is bad. You may have only one head bad, however if it was a faulty rebuild you could have more issues.

 

Problem doing one of these jobs with these engines is the push rod order and setting valve lash. Just a PITA.

It’s straight forward otherwise however if you start looking a big repair bill to pay someone do the job it might be cheaper to swap the motor out again with a used engine.

 

 

 

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[AMC86Kid]

i think I'm gonna have someone else do it its not worth getting a different engine i have worked on this one enough now 

[Green Mesa XJ]

I get it. You’ve poured a lot of effort into getting it running to have this issue, it breaks the heart.
I had a car in my late teens I save from a junk yard that was prone to BHG.

I don’t get why a remanufactured engine has a headgasket problem. It’s a simple engine.




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[AMC86Kid]

i might have blown the gasket by running it to hot or maybe they didn't put it on straight who knows

but will definitely find out after i take it apart 

just want to get it up and running so i can go to the lake with it 

[Green Mesa XJ]

Did you notice if there was a heat tab that reacted to the heat? Normally on the cylinder head after rebuild.

 

Are you going to do the disassembly or farm it out?

 

Only reason I’m asking is there are a few tips to doing it. Common sense stuff like making a box with holes to line up the push rods exactly as they come out, I believe there is a tab on the cylinder head between the block where you can pry up to free the head.

 

I would compression test to identify which side is faulty. If your have better peace of mind replacing both sides that’s fine too.

Both cylinder heads are the same, no left or right. Cylinder head is the same 1985-1995 gm (casting # 14054884 aka 4884 ) exceptions are 1985 & 86 Jeeps which got 1984 cylinder heads which are lower HP)

 

 

I used the severe duty head gasket from fel-Pro 512sd, which I believe is only 2.8 & 3.1 v6. I think 3.4 is bored out more and has a slightly different gasket. Not sure if they make a Severe Duty gasket for the 3.4. Speaking of I wonder if whoever rebuilt the 3.4 used the correct head gaskets??

 

 

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[AMC86Kid]

I'm gonna take the heads off change the gaskets with new ones and get the headers resurfaced then see if i get as much combustion as i did with the old gaskets in my radiator 

should be pretty simple i will start on it tomorrow 

[Green Mesa XJ]

Just FYI you might get away with not sending the heads off to be resurfaced, there not like aluminum heads in that respect but it you don’t have the tools or confidence you probably should play it safe with a machine shop.

Usually the gaskets on these engines are forgiving of minor variances.

Check the push rods are in good shape and make sure it all goes back to the same lifter because of the wear pattern.
Setting the valve lash makes me nervous, I still haven’t installed the motor I’ve set them on yet.




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[AMC86Kid]

there is a machine shop in town that will resurface them for just 30 bucks a piece 

so its a pretty good deal to me