Amazing overheating problem...desperate

[ogden lafaye]

Bad thermal fan clutch

Hey RedFish...thanks...however fan works properly and is mounted the same since new. I have since replaced the 195F thermostat with a 180F and drilled it, also changed the pressure cap 16 lbs. with a 13lb. lift type pressure cap.

Amazing but it hasn't heated up once since then. Keeping my fingers crossed...

A crack in an exhaust valve seat is a good clue, however all symptoms of overheating due to a crack have disappeared. There are no bubbles in the water on start or after heating up. I would think a crack would manifest symptoms other than overheating? No exhaust crackling or intake back fires.

However, I am told that a crack in a head (somewhere) is in all likelihood the culprit. I am carefully optimistic at this point as everything has worked well for over a week.

 

[nm9stheham]

Interesting.... lift caps are known to be more iffy than non-lift caps.....maybe just a POC 16 lb cap. Brand?

And 13 lbs would allow it to boil more easily. Perhaps the lift cap and lower pressure and drilled is allowing the system to bleed the air out better. And may be the temps are colder.....

A small head crack will sometimes show up a a slight but persistent overtemp. It can be very mild; I raced one for several races that way and the crack was so small that it never really got super hot, just up to the H range.

Well, here is hoping you have it fixed!

 

[Inertia]

It's been my experience a crack(ed seat) into water, will increase coolant pressure till it pumps enuff of the coolant out the overflow to cause it to overheat...

 

[mr gtx]

Might have to pull freeze plugs towards the rear of motor to see if there's a build up of rust& crud could be problem.

 

[nm9stheham]

It's been my experience a crack(ed seat) into water, will increase coolant pressure till it pumps enuff of the coolant out the overflow to cause it to overheat...

Guess it depends on the size of the crack....

 

[ogden lafaye]

This symptom caught my eye:
"-YES, pushes water out of overflow tank then bunches of hot hot steam"

This is quite abnormal, and indicates possibly that:
- The system is not getting anywhere near all the air out at filling (despite the hole in the t'stat). The coolant in the engine is flashing into steam in short order, and once the t-stat opens, just pressurized steam is coming out of the engine and pushes through the water in the overflow tank. The pressure would have to be somewhat high to do this, which indicates hard boiling in the block or heads. And I can't tell you how well or poorly the rad cap will seal in the presence of just steam rather than hot coolant.

Can I suggest that you go through the burping process slowly and repeatedly and with just 1-2 minutes of run time at any time, then allow a cooldown and repeat? Also, make sure the truck is pointed up hill; put it on a jack if you need to.

Another suggestion- Put a pressure gauge cap on the rad and stop every minute to see what is going on.

Questions:
- Does it do this if you start cold and idle, and not drive?
- What radiator? Does the cap actually match the rad opening for 100%
- What coolant is being used?
- Heater core hooked up? Do you open that when you burp the air out?
- Engine mounting normal? Not sloped 'downhill'?
- Any pix of the installation that you can share?
- Cooling fan(s) set up?
- Any excess water in the exhaust? Indicating that coolant is leaking out an exhaust port overnight?

- Yes it will do it if I start cold and idle, not drive...
- Good fitting, new 13 lb cap...
- Plain water and 1+ quart of antifreeze
- Heater open...installed large ball valve...wide open
- Stock mounted engine, I park the truck pointed slightly uphill\
- No "installation" totally stock truck/engine/exhaust EVERYTHING stock
- Cooling fan operates normally, belt OK
- No water in exhaust, no fluid loss overnight

- I recently installed that new 13 lb. (lift arm type) radiator cap
- I shortened and lowered the hose out of the top of the radiator, it is below the radiator fill opening now.
- I installed a 180 deg F. thermostat and drilled a small hole in it.

The problem seems to be cured folks. It has not done it for 6 or 7 trips now.

I really believe the 195 deg F. thermostat just wasn't opening because of air around it and the block got super hot and the pressure was going backwards through the water pump and out the overflow tank. When I bled off the pressure and added cold water, the thermostat was already opened...and the rest of the day was uneventful. It was just that start up and drive off in the morning (1 mile at 30 mph, then 2 miles at 55 mph)steam out from under the hood...blooey, stop, let off pressure, add water...everything normal again.

Dodge did say that the alternate choice in thermostats for my system was 180 deg.F

 

[ogden lafaye]

We shall see he says, with bated breath, fear still flashing in his eyes.....I did ALL the work myself and at 76 years old it was still interesting and a type of fun we all know. Now, if I could just find someone to do my auto transmission A727 I believe, or swap it out for a good one. The truck has lasted 300,000 miles and should be good for another 150,000...everything works fine, no major dents just farm yard stuff. I rebuilt everything else then the tranny and radiator traumas began...typical machinery reaction to loving care...laughter...I DO take extraordinarily good care of my vehicles. The yanking towing pulling overloading is what a farm pickup is for...its a TRUCK darn it...laughter

Thanks everyone

 

[ogden lafaye]

Might have to pull freeze plugs towards the rear of motor to see if there's a build up of rust& crud could be problem.

Thats interesting and might relate to my problem. I DID change a freeze plug towards the rear recently and yes, there was a bunch of waxy/grease looking crud behind it. I used a radiator flush on it about 3 times with no cessation of the over-heating problem however.

20 years ago I flushed the radiator and it all came out black...subsequent flushes have barely been discolored.

Now things are back to normal...not to say your suggested ball of crud wasn't to blame, just that if so, it has shifted favorably...

Thanks for your input.

 

[ogden lafaye]

Interesting.... lift caps are known to be more iffy than non-lift caps.....maybe just a POC 16 lb cap. Brand?

And 13 lbs would allow it to boil more easily. Perhaps the lift cap and lower pressure and drilled is allowing the system to bleed the air out better. And may be the temps are colder.....

A small head crack will sometimes show up a a slight but persistent overtemp. It can be very mild; I raced one for several races that way and the crack was so small that it never really got super hot, just up to the H range.

Well, here is hoping you have it fixed!

Yes thanks, I switched to 13 lbs.lift cap and 180F stat...lowered the upper hose so that it was below radiator fill opening......so far, OK (fingers crossed) see posts below

A crack in the heads/block would be the death nell...I am just too old to be pulling and magnafluxing heads and blocks. I hate to get rid of a truck that is almost computer free and stripped down to the bone accessories wise. I ran a business for years and had about 15 or 20 of these 318 Dodge trucks and none were newer than 1990...they all ran over 200,000 miles and we abused the hell out of them. Average mileage at full failure time was 250,000 miles. All but one A727 trannys made it the whole way. They were always overloaded and we used 2nd gear, wide open throttle often to attain and maintain speed. The engines usually dropped a valve. I changed 2 radiators and had one right front suspension complete, just ripped out of the truck...The brakes lasted 150,000+ miles.

A Dodge 318 was a hell of a truck.

 

[famous bob]

Yes thanks, I switched to 13 lbs.lift cap and 180F stat...lowered the upper hose so that it was below radiator fill opening......so far, OK (fingers crossed) see posts below

A crack in the heads/block would be the death nell...I am just too old to be pulling and magnafluxing heads and blocks. I hate to get rid of a truck that is almost computer free and stripped down to the bone accessories wise. I ran a business for years and had about 15 or 20 of these 318 Dodge trucks and none were newer than 1990...they all ran over 200,000 miles and we abused the hell out of them. Average mileage at full failure time was 250,000 miles. All but one A727 trannys made it the whole way. They were always overloaded and we used 2nd gear, wide open throttle often to attain and maintain speed. The engines usually dropped a valve. I changed 2 radiators and had one right front suspension complete, just ripped out of the truck...The brakes lasted 150,000+ miles.

A Dodge 318 was a hell of a truck.

the first thing I thot of was going to a 180 thermostat, way back in the post .

 

[nm9stheham]

I am thinking lowering that upper hose fixed the issue.... pretty much impossible to get all the air out with it sticking up high.

 

[ogden lafaye]

Well, you got the "jumble" part right. That was very hard to read, bordering on incomprehensible.

@rustedwrench
"Instead of jumping around randomly, think about what is different between engine cold and engine warmed up."

This is a hell of a good post...thanks.

I installed a large ball valve in the heater hose just for such a check. The thermostat was NOT heating up enough to open before overheating occurred. A lot of what you say is part and parcel to the problem and all your tests were tried.

Now that it runs normal with a 180F. stat and 13 lb.lift cap...on reflection, I believe you had a better overall picture of what was occurring.

Thanks again.

 

[ogden lafaye]

the first thing I thot of was going to a 180 thermostat, way back in the post .

@famousbob...yes you did and you know, NAPA looked into it and said a 180F. stat was recommended by Dodge as an alternate. I have a funny feeling the truck was "sorta" sorted on the assembly line for towing...it was a US Government truck I picked up at auction dirt cheap and almost new. It had an oil light problem at low speeds and although they changed the sending unit...it still indicated low oil pressure so they sent it up for auction. I put another sending unit in after checking the oil pressure with a gauge. It was 40lbs. at idle...laughter. Almost new truck for $2600

But anyway, it had an inner radiator cooler for the tranny and an outer tranny cooler. Extra heavy duty suspension in the rear, A727 tranny...so that original 195F. stat might have been part of a towing package. The two row radiator doesn't fit the package intent I would think.

Well, its been fun...thank you

 

[ogden lafaye]

Impeller slipping on water pump shaft when cold??

You must be an old timer...yes, there were cast iron impellers years back and they used to slip when cold and then grip once you warmed up...eventually you had to change the water pump.

I pulled the water pump and it was a stamped impeller and after all those miles it was as tight as a new one in all planes and directions. Some of these 318 engines will go 300,000 miles and not even burn oil much less need a water pump. I revved my business vans with overloads like concrete forms, machinery, heavy tows etc. and they eventually had valve keeper and stem problems but this pickup has never been overly revved or abused engine wise.

Pulled a lot of stumps however...laughter.

 

[ogden lafaye]

To check if the impeller is slipping,, fab up a tool as in pix,, you can take the by-pass hose off,,,, send the tool down the inlet and snag the impeller,, then turning the fan.. it saves removing the pump..

Being a new pump,, you can be fairly confident the vanes aren't rotted off..

hope it helps

The slipping impeller was a good clue and your slip checking "tool" and procedure is genius.

My plea for help has been met with a lot of ingenious ideas.

Thanks all...

 

[ogden lafaye]

Lots of good suggestions here. You will have to go through each step in some sort of order. I will throw my two cents in. Is there anything that could be putting a load on the engine causing it to do too much work? Something that maybe would ease after a few miles. The trans problem seems closely related, maybe a converter problem. Maybe the parking brakes take a little time to release. Check the rear end after driving for a while. I've seen some that glow red they drag so bad.

Thanks for the suggestions but, no...nothing like that. This truck usually starts out in 3rd (high) gear. Quiet, very quietly it moves off...sometimes it stays in 1st gear for a mile or so but I drive 20 mph until it finally shifts to 2nd or 3rd. There are other transmission problems but drag isn't one of them. This truck glides quietly through the day and seems to coast extremely well. If it wasn't such a magical old thing I would have junked it lately. One guy told me I might be driving that transmission another 5 years...laughs. My wife and I enjoy it...late at night in the winters it is warm and quiet. Hardly needs to be steered...its a LWB so she hauls sheet rock in it sometimes. You can put a mattress in the back and spend the night looking at stars and kanooodling. Most of the paint peeled off years ago so I rattle canned it flat white...looks nice from the road. We bought an old derelict house and have been rebuilding it...we hauled 30 or so loads of trash in the pickup and 25 or so loads in the trailer...the dump is 5 miles away...2750 lbs. was the biggest haul, all in the truck AND trailer...so it is sort of retired nowadays.

Looking for a A727 transmission...thanks all. (In SW WA. State, Naselle WA)

 

[ogden lafaye]

before replacing thermostat 5 times I would have tried no thermostat

Of course...this was done...ran cold...didn't overheat. Thanks

 

[ogden lafaye]

Exactly why I didn't and won't read it.

Well, once a lot of people picked it up the suggestions came fast and true. I tried everything I hadn't thought of and we all seemed to have a good time. The truck runs OK now.

If everything was simple and conversations terse.....it wouldn't be fun, it would be like... church.

 

[Marcohotrod]

Of course...this was done...ran cold...didn't overheat. Thanks

shoots a big hole in the old idea of no thermostat allowing the coolant to run thru the radiator too fast and causing her to run hot! :sign12: - coolant running fast. thanks for the update Og

 

[paulscars]

before replacing thermostat 5 times I would have tried no thermostat

x 2 lmao :sign3:

 

[paulscars]

shoots a big hole in the old idea of no thermostat allowing the coolant to run thru the radiator too fast and causing her to run hot! :sign12: - coolant running fast. thanks for the update Og

the main reason for having a tstat is for 2 reasons.. # 1 maintaining a steady engine temp for proper lubrication. 195 is good. a little higher is fine. too low is not good. that is why you should never run your engine without a tstat unless you are just testing. # 2 is to get heat for your nuts when driving in colder climates. :burnout:

 

[ogden lafaye]

Very fine fracture in exhaust valve seat?

To everyone...thank you.
Problem solved. There was a rubber expansion plug in the water jacket. It started contracting at night and very slowly leaked water. In the morning, water level appeared full but once the engine warmed up it (Rubber expansion plug) expanded. Added water and the truck ran great for rest of day with no water leakage. Repeat problem every few days. I put a metal expansion plug in and all is OK.

 

[512Stroker]

Never thought of that twist...but you would think it would not recur with a new pump, and would eventually slip enough to do it all the time.

I had this issue with a new Milodon BBM water pump.

 

[ogden lafaye]

This symptom caught my eye:

nm9stheham analysis came closest in that a freeze plug (rubber) periodically leaked when cold at night. Water Jacket Leak: correct! It leaked off and on and a radiator check in the morning often indicated full! which might have been an air/bubble problem. I replaced the rubber freeze plug with a metal one (located behind the starter, thank goodness...took a 1/2 hour. Thanks for all the help folks.
"-YES, pushes water out of overflow tank then bunches of hot hot steam"

This is quite abnormal, and indicates possibly that:
- The system is not getting anywhere near all the air out at filling (despite the hole in the t'stat). The coolant in the engine is flashing into steam in short order, and once the t-stat opens, just pressurized steam is coming out of the engine and pushes through the water in the overflow tank. The pressure would have to be somewhat high to do this, which indicates hard boiling in the block or heads. And I can't tell you how well or poorly the rad cap will seal in the presence of just steam rather than hot coolant.

Can I suggest that you go through the burping process slowly and repeatedly and with just 1-2 minutes of run time at any time, then allow a cooldown and repeat? Also, make sure the truck is pointed up hill; put it on a jack if you need to.

Another suggestion- Put a pressure gauge cap on the rad and stop every minute to see what is going on.

Questions:
- Does it do this if you start cold and idle, and not drive?
- What radiator? Does the cap actually match the rad opening for 100%
- What coolant is being used?
- Heater core hooked up? Do you open that when you burp the air out?
- Engine mounting normal? Not sloped 'downhill'?
- Any pix of the installation that you can share?
- Cooling fan(s) set up?
- Any excess water in the exhaust? Indicating that coolant is leaking out an exhaust port overnight?

 

[famous bob]

This symptom caught my eye:
"-YES, pushes water out of overflow tank then bunches of hot hot steam"

This is quite abnormal, and indicates possibly that:
- The system is not getting anywhere near all the air out at filling (despite the hole in the t'stat). The coolant in the engine is flashing into steam in short order, and once the t-stat opens, just pressurized steam is coming out of the engine and pushes through the water in the overflow tank. The pressure would have to be somewhat high to do this, which indicates hard boiling in the block or heads. And I can't tell you how well or poorly the rad cap will seal in the presence of just steam rather than hot coolant.

Can I suggest that you go through the burping process slowly and repeatedly and with just 1-2 minutes of run time at any time, then allow a cooldown and repeat? Also, make sure the truck is pointed up hill; put it on a jack if you need to.

Another suggestion- Put a pressure gauge cap on the rad and stop every minute to see what is going on.

Questions:
- Does it do this if you start cold and idle, and not drive?
- What radiator? Does the cap actually match the rad opening for 100%
- What coolant is being used?
- Heater core hooked up? Do you open that when you burp the air out?
- Engine mounting normal? Not sloped 'downhill'?
- Any pix of the installation that you can share?
- Cooling fan(s) set up?
- Any excess water in the exhaust? Indicating that coolant is leaking out an exhaust port overnight?

Rise the front of the truck about 16" higher than static, let it set over night w/ th4e cap off after filling , note where the level is compared to when u left it last night. = AIR