Tech: At wits end with an overheating motor, long post

Fords can take a good amount of heat before they blow a head or head gasket.

Firing order is right for the 351w, checked that more times than I can count. Can't do the intake crossover as the ports are for my heater hoses.

Overflow never filled, but would get the occasional fluid in it from time to time before. I haven't run it with the system pressurized yet as I was still trying to bleed bubbles and didn't think that would affect it.

215 is hot for this motor. This motor is designed to run 160-180 from freshwater intake (ski boat motor). 180-200 is normal operating temp for a Ford 351w.

I'm going to watch the bubbles intently and see. It might just be head gaskets. But with this old girl, that's one of those things I really didn't want to pull apart unless I had to. My concern is that with a leak down test, on a 1989 engine, I might just get a lot of cylinder/ring leakage and won't be able to tell if it's head gasket related. How do you know if it's your head gasket from a leak down test?

EDIT: Perhaps a cooling system pressure tester might be the better route. That would in theory find it as well wouldn't it? Without the risk of possible blow-by giving a false reading.

customcj7 said:

See, my brain is fried, that would make more sense. Nope, airflow is not restricted on the front. Even angled my box fans towards the front to ensure fresh cool air gets pulled by the radiator fan.

And as for the bubbles after the t-stat opens, that's kicker, I get random bubbles from time to time, and then eventually they stop which would lead me to believe I got them all.

As for the water pump, it's hard to tell with the new radiator. The cap is on the opposite side of the neck, so short of taking off a hose while running and seeing fluid pump out, I don't know how else I can tell.

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617_Racing said:

I think he was implying the airflow through the radiator, not the coolant flow inside of it.

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This. As crazy as it is I was helping a friend change the radiator in his xj and we had a box sitting on top of the winch and it was blocking air through the radiator and making it run hot. Some times after you've done all the in depth stuff like you've done it's the simple little things that you miss was the reason I asked. It's a funny story now but back then we were both about ready to burn his jeep to the ground.

215 with the fan on? Get a new fan. Taurus/volvo would be my choice.

Take the upper radiator hose off and back fill the water pump. I had a huge air pocket back there on my LS when i went to fill it up initially.

Do as you said and park up a hill and let it sit for 10 mins or so. Run it for a min or two and check again. Repeat until no more air. Bleeding a cooling system sucks sometimes.

Re: Re: Tech: At wits end with an overheating motor, long post

customcj7 said:

Firing order is right for the 351w, checked that more times than I can count. Can't do the intake crossover as the ports are for my heater hoses.

Overflow never filled, but would get the occasional fluid in it from time to time before. I haven't run it with the system pressurized yet as I was still trying to bleed bubbles and didn't think that would affect it.

215 is hot for this motor. This motor is designed to run 160-180 from freshwater intake (ski boat motor). 180-200 is normal operating temp for a Ford 351w.

I'm going to watch the bubbles intently and see. It might just be head gaskets. But with this old girl, that's one of those things I really didn't want to pull apart unless I had to. My concern is that with a leak down test, on a 1989 engine, I might just get a lot of cylinder/ring leakage and won't be able to tell if it's head gasket related. How do you know if it's your head gasket from a leak down test?

EDIT: Perhaps a cooling system pressure tester might be the better route. That would in theory find it as well wouldn't it? Without the risk of possible blow-by giving a false reading.

Click to expand...

Best way is to watch the coolant level, it will rise. True you may have weak rings but if it's running good, doubt you will have a lot. If you feel air coming put of the dipstick tube or oil cap, then you will know.

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if that 351 was built by pleasure-craft marine your head gaskets are more than likely just fine. if you are still worried about it go to auto-zone and rent a hydrocarbon tester, it is basically a turkey baster with a fluid that changes color in the presence of hydrocarbons in the coolant system. on a side note throw that radiator cap away. go to your local parts house and buy a 6lb cap and hook up an overflow ( be sure to extend the overflow tube to close to the bottom of the overflow jug, that way when the engine cools it pulls fluid back into the coolant system)

Coincidentally 84Mallcrawl a buddy just mentioned the same "test kit" to me. I'm going to give it a try.

https://www.napaonline.com/p/BK_7001006

It was a PCM motor, can almost see the PCM on the valve covers. I'm sure I'm being overly cautious on the heads, but I'll eliminate them as a cause and then keep trying to source the air bubble it probably is. With being drained so many times now I'm sure I had air everywhere.

yeah I doubt you have a blown head gasket. I have seen one with a blown head gasket, and it was leaking oil out from under the head. those heads were a son of a .... to pull. The gaskets were bonded to the head and the block.

1. yep grab a HG tester and eliminate that possibility first.
2. yep again, put your radiator cap on, bring the motor up to temp, park the nose uphill, (the steeper the better) shut it off and check it 20-30 mins later
3. If this doesn't work, I'd pull the thermostat out and verify it's opening and closing properly. Could be stuck closed, doubtful but possible. I think there's a way you can put the stat in a pot of water on the stove and watch it open when the temp gets up to the stat's degree level.

if yall havent seen it the make a tool called cooling system air evac kit. it will get the air pockets out and refill the system

tallnate said:

1. yep grab a HG tester and eliminate that possibility first.
2. yep again, put your radiator cap on, bring the motor up to temp, park the nose uphill, (the steeper the better) shut it off and check it 20-30 mins later
3. If this doesn't work, I'd pull the thermostat out and verify it's opening and closing properly. Could be stuck closed, doubtful but possible. I think there's a way you can put the stat in a pot of water on the stove and watch it open when the temp gets up to the stat's degree level.

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I usually check a new tstat in a pot of water before I ever install it. Just to make sure I don't waste time installing a defective one.

Did you remove the plastic caps out of the radiator where the hoses hook up?

Intake gaskets on correctly so they aren't blocking the coolant passages?

Cooling fan moving air the right direction?

I did a boil test on the T-stat before I installed, checked out okay. I'm going to try and run it tomorrow with the cap on and just give it some serious movement versus just revving it to see what happens.

I picked up the exhaust gas test and will do that tomorrow as well as I'm not getting any bubbles of any kind anymore. I jacked up the whole jeep as high as my jackstands would go this morning and only got a few bubbles.

grcthird said:

Did you remove the plastic caps out of the radiator where the hoses hook up?

Intake gaskets on correctly so they aren't blocking the coolant passages?

Cooling fan moving air the right direction?

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No plastic caps were present. Haven't removed the intake ever, still factory setup. And the fan is pulling air like nobody's business.

Be sure to post what the outcome is when you figure it out.. Hate it when post are left unanswered once a problem was found.

The only other thing I can think of is either the new water pump impeller is spinning on the shaft, or since you sped up the pulley speed now it moves the coolant faster and not enough heat transfer is happening, although I really doubt the last part is what's wrong.

I've seen somewhere that left over casting crap that didn't get removed from a pump caused an impeller to not spin and overheat an engine...it may have been somebody on here.

I have the coolant refill tool that pulls a vacuum on the system if you want to drag it to my shop in Argo.

is the water pump a reman?

the dum dums may have put the wrong impeller on it. I've seen stranger things.

TBItoy said:

is the water pump a reman?

the dum dums may have put the wrong impeller on it. I've seen stranger things.

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Yup manufactured in China under head machinists sum ting Wong


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Well it's a duralast special so there is no telling with the water pump. I've wondered as well. Hell it could have been a regular rotation put into a reverse rotation box for all I know, I was a dumbass and didn't check the fin direction before I put it on.

I'll put an answer up hopefully soon. With mothers day Sunday, and yesterday was our anniversary I didn't even touch the jeep. Hopefully today I'll take it down the road and see what happens. As best as I can tell I've gotten almost all the air out. This will run it a bit to see if it goes down, then I'll do my exhaust gas test.

After that, I have no idea. I guess I'll have to pull the water pump back off, pull the T-stat to check it, and start my diagnosis all over.

I had one question about cleaning the block. It's an old marine block which means it never had treated water which means ever year when it sat out over winter, it probably surface rusted. Now I've looked into the ports as best as I can and I didn't see a rusty mess, but the old cast iron is pitted. I used some prestone add a cleaner in the old radiator to try and see if I could clean out any gunk, and not much if anything came out. Should I have used something else? I don't want to use aggressive cleaner on my new aluminum radiator. But if I had to I can throw my old radiator back in and let that thing take the abuse.

I wouldn't think it would be that as before I did all this it was operating fine. It had a 195 T-stat and was keeping it there. I'm willing to bet if I had a lower T-stat it would have run cooler. But now, with a new radiator, fan, etc I'm cooking.

customcj7 said:

I did a boil test on the T-stat before I installed, checked out okay. I'm going to try and run it tomorrow with the cap on and just give it some serious movement versus just revving it to see what happens.

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Hey Eric, you put the thermostat in with spring end of the thermostat facing into the engine correct?

Put a 160 degree stat in next time you pull it apart.