Intake manifold drastically different temperatures

[blueday]

Just picked up a 90 GW. Most everything is there and from what i can tell stock. Bought it not running but would turn over. Replaced some essentials and it runs now. Currently I have not let it over heat yet according to the gauge, it'll get up to about 240 and I turn it off.

Trying to diagnose the problem, the coolant is pretty rusty looking. I drained it, filled up with water and a bottle of flush/cleaner, replaced can clutch, but Stat (190) and rad cap. It'll get to about 230 and hold while idling and doing g 25-30mph around neighborhood.

I got my ir temp gun out and while running it's reading 195 on tstat housing/front of intake and 330 at very back of intake.

Stupid question, but is that normal? Or do I possibly have a big airpocket back there or something else I might be unaware of.

Gonna flush everything well this weekend and use my coolant vacuum system tool to fill it up.

Any help/advice would be great.

Rya

[Stuka]

A few things I would check.

Start it up cold, with the radiator cap off. Once the stat hits 190, you should start to see the water move. Its also good to look for consistent, small bubbles which could mean you have a head gasket leak, and the cylinder is pumping air into the coolant system. Though I assume if it was blowing steam, you would have noticed.

If you turn on the heater, does it blow hot air? And does the temp go down at all? If the air isn't hot, it suggest you have a blockage in the system, or the water pump impeller is rusted away and not moving water. If the temp goes down, it means your radiator is likely blocked to some extent.

[blueday]

I'll double check the coolant with the radiator cap off. I looked before I swapped tstat but didn't notice anything. Definitely no steam out of radiator with cap off before new tstat and no white smoke coming out of the exhaust.

Does the intake have coolant passages running through it front to back? I've never worked on these motors before. I come from sbc world.

I'll test the heater and watch temp tomorrow night. Moving the ir gun around the radiator and hoses are the coolest in the system. I'll also double check heater.

Previous owner had it since 2018 I believe and had it running around then. Has been sitting up since.

If I had a blown head gasket I'm between Cylinder and coolant passage I'm sure it would push air in the coolant and also seems like once cooled off it would leak coolant into Cylinder and I'd see some white smoke out the exhaust on start up plus maybe milky oil by now?

Picture of the GW and making sure I'm posting pictures ok.

[Srdayflyer]

i have seen pictures of non running fsj's having cooling issues, and several have found the waterpump impellor blades severely rusted away or completely gone, , move little or no water will get you high temps, not saying this is the case but a possible issue to look at

[Stuka]

Does the intake have coolant passages running through it front to back? I've never worked on these motors before. I come from sbc world.

I'll test the heater and watch temp tomorrow night. Moving the ir gun around the radiator and hoses are the coolest in the system. I'll also double check heater.

Previous owner had it since 2018 I believe and had it running around then. Has been sitting up since.

If I had a blown head gasket I'm between Cylinder and coolant passage I'm sure it would push air in the coolant and also seems like once cooled off it would leak coolant into Cylinder and I'd see some white smoke out the exhaust on start up plus maybe milky oil by now?

Yes, coolant does go through the intake manifold. But its from side to side, not front to back as I recall.

A blown head gasket seems unlikely with what you are seeing, but I figured it was worth nothing.

I am still leaning towards the water pump impeller being gone due to rust from sitting. Though it could also be a plugged radiator or something.

[ak_garner]

Lowest hanging fruit - What's the condition of the radiator? WIth your IR thermometer, you can check the corners to see how well it's cooling by checking the temp drop through it. Might just be cruded up inside, which rusty coolant would indicate. Even a flush might not get all the sediment/blockage resolved.

[blueday]

The radiator looks like the previous owner may have changed it. Radiator does have a much lower temp than the motor, lower/upper hose Temps 156/180.

Here's a few quick videos I took to hopefully help a bit. Thinking about it the videos with the radiator open the steam bubbles I would imagine is from the radiator cleaner I put in with just water. I tried turning the heater on but no air comes out the vents at all and fan (I guess?) Makes a loud whinning noise. Guess I'll figure that out eventually. I also did a quick video of it reving to show no white smoke out of exhaust.

I'll pull the water pump this weekend and go ahead and replace. It'll get a good flush with some actual coolant.

Any thoughts comments from the videos are welcome to try and diagnose this.

Thanks,

Ryan

https://youtu.be/I55poigtxS0

https://youtube.com/shorts/OxRljXbOyaU

https://youtu.be/efb5In7DGH0

https://youtu.be/I_UenevlmCg

[letank]

good videos, the fan looks really woobly, make sure that the fan clutch is not separating from its axis.

add a little more water to have a smoother flow when looking at the radiator neck, it could be a bit low.... that top tank takes a lot of fluid.

If I see correctly it is only the back driver's side that is cooking... at 296F, remember that the EGR channel is near by so you are getting some hot exhaust conduction... try to move the IR away from the EGR. The back passenger side is in the 190F ish

[candymancan]

Coolant looks nasty.. and low.. if it were hot and full.. itd be pouring out the top of the radiator. Once the engine was at operating temps.

I woukd drain that mess.. take the lower hose off.. and the thernostat and i would flush that engine out with a garden hose.

Then refill with distilled water fully... run it for a bit with the thermostat out. (Meaning the housing on but no t stat to the hose water circulates with the distilled.. then drain again.. and repeat again with no distilled.. this way you can get the hose water out and diluted enough... Then i would pour in 100% coolant and some more distilled water until you get the right mixture with one of those floats you can buy at the autoparts store. Also replace the hoses if theyre squishy and replace the thermostat so you know its new.. its cheap.

In all youll probly need 2 bottles of 100% antifreeze. And like 10 gallons of distilled water to flush it. Antifreeze is cheaper at walnart fyi. Get the green prestone

Then check this again.

Also lose the zip ties on the spark plug wires.. It isnt good practice to have wires touching eachother it can create spark knock. Get some proper wire splitters that keeps them seperated. They sell em in the auto part store.

The 288f temps youre reading in the back is exhaust gas from the egr.

Point the ir gun at the last intake manifold bolt.

Get that gunky coolant out of that engine before you di anything else. The steam youre seeing is just steam.

Replace the heatercore blower motor.. simple easy to do.


Your ticking sounds like an exhaust leak..

Welcome to the world of fixing old cars lol.. Get some wrenchs and go to town

[tgreese]

... the EGR channel is near by so you are getting some hot exhaust conduction...

This is a good point. I would expect the manifold in the vicinity of the EGR valve and the carburetor heater to be hot. The heat riser directs 100% of one bank of exhaust gas through the intake manifold if closed. That will be HOT. The heat riser should open at operating temperatures and exhaust gas will then be available at low pressure through the manifold. This is enough to supply the EGR valve. While the engine warms, 1/2 of the total exhaust gas goes through the intake manifold cross-over passage, at considerable higher flow and pressure. This will get rocket hot if the heat riser valve does not open as the engine warms up.

[Stuka]

The intake being hot around the EGR isn't his issue though, its just something he noted. They issue is that the engine will overheat while sitting and idling.

[candymancan]

Look at his rusty coolant. Change the t stat.. change and flush all the coolant. This is probably the issue.

[Stuka]

Look at his rusty coolant. Change the t stat.. change and flush all the coolant. This is probably the issue.

He already has.

[letank]

Coolant looked decent.... here is a bad coolant, and you can see the level a bit below the radiator cap neck

86RustycoolantDSL.jpg

[Scotty54]

One thing to add regarding manifold temp - AMC racers often add a coolant passage to the rear of the manifold to circulate coolant right to left in the rear of the engine. I don't think any of the off the shelf makers have this but I have seen exotics like Herman Lewis intakes or similar with this passage added. The F to R difference is normal.

[blueday]

One thing to add regarding manifold temp - AMC racers often add a coolant passage to the rear of the manifold to circulate coolant right to left in the rear of the engine. I don't think any of the off the shelf makers have this but I have seen exotics like Herman Lewis intakes or similar with this passage added. The F to R difference is normal.

Hey that's good to know and makes me feel better about the drastic temp differences. Thanks.

[blueday]

Alright so I sucked it up and pulled the pump, tstat and radiator. I did expect to see the water pump impellers rusted off as mentioned but surprised to see everything there. If got replaced anyways. More surprised the previous owner/mechanic left me a broken off wp bolt in the block (even start drilling it). I tried torch and easy out, nope. Ended up drilling larger and larger til I got what was left to come out and cleaned up block threads. PIA by the way.

I just replaced tstat last week and it looked like this. Took about 10 minutes of running water through the passages to get it to run clear. Then moved to the heater core to flush, flushed the radiator too. Pump pump back on and ran it with the water hose on the inlet (don't laugh at my setup, it worked). Took about 12 of those smaller buckets full to get to start running clear even after all the previous flushing. Anyway, buttoned and filled everything up and so far so good.

Also had a rear door handle fall off which seems fairly common. Trying to save some money I made some walls out of tape and poured some epoxy in there good as new.

Still not sure why the "coolant" was so nasty. I'm thinking they filled with just water and no antifreeze could be a reason for all the rust.
























Ryan

[Stuka]

Did the truck sit for an extended period before you got it?

This reminds me of my '65 Mustang that sat for a few years before I got it. It was my daily driver. And every day for weeks after I got it I would pull the radiator and flush the system because rust flakes would plug all the tubes in the radiator. I got pretty good and doing this after a few days. Eventually it got good enough to where I could put anti-freeze back in it and never had to worry about it again.

[letank]

What a surprising color, usually it is rusty, but yours seems to more muddy.

Remember to use steam distilled water not deionized... and I flushed mostly rusty water for about 30gallons 6x5 gallon bucket on the receiving end.

Good set up, I used the prestone flush system connected to a garden hose, engine running until the liquid is as clear as can be

CoolantVomitDSL.jpg

[blueday]

It got distilled water and coolant mix...... still green from what I can see in the radiator. Thank yall for the help and advice with this.