6.9 idi problems

[Kyle akers]

Hi I’m new to the 6.9 Idi thing just swapped one in an old 68 international and I’m having a problem with it running hot just put in a bran new 3 row alluminium rad and electric fans in but the temp just climbs up there it has even started to set the pop off valve off even when it’s not warmed up any suggestions on what to do or look for

 

[IDIBRONCO]

How long does it run before getting hot? Is it building up pressure in the cooling system? It kind of sounds like it is. Does the pressure build quickly or slowly?

 

[Kyle akers]

It runs for about 40 min before it starts to climb and seems like it starts to pressurize instantly

 

[Kyle akers]

Im not seeing any white smoke from the exhaust like a headgasket but I read they can blow through a cooling passage it seems to pressurise faster than any motor I have ever had witch worries me .it only has 180.000 miles on it pulled out of a 84 e350 for my project truck just more or less have no clue whatsoever about this motor just that it was reliable

 

[IDIBRONCO]

Are you seeing any bubbles in the coolant? That's the easiest way to tell if you're getting cylinder pressure into your cooling system. When the engine's cold, pull off the radiator cap and then start the engine. If you can see bubbles in the radiator, then you're probably looking at a head gasket.
This one is puzzling. The instant pressure in the cooling system sounds like head gasket, but if it was, I can't see how it would run for 40 minutes before getting hot.

 

[snicklas]

Did you change the thermostat, or do any work to the engine? Or did you just pull it from one and move it “untouched” to the IH? The lower radiator hose isn’t being sucked shut by chance? These engines move a ton of coolant and can suck the lower hose shut and cause all kinds of strange cooling system issues/symptoms.

Also, whereabouts in Indy are you.... I’m out east in Greenfield......

 

[Kyle akers]

I have cleaned out the cooling passages and put a new thermostat in I will check for bubbles in the rad the lower rad hose did not appear to get sucked shut at all and I am in Marion county right next to green wood

 

[snicklas]

I get down that way fairly ofter.... if you need another set of eyes.... I could maybe stop by.....

It doesn’t happen to be red? I saw a red IH pickup on a rollback a few weeks ago when I headed to Sams.... it was coming north on Emerson and went west on County Line.....

 

[Kyle akers]

No it’s green I will do some investigating on it tonight

 

[FrozenMerc]

It is one of two things.

1. If the temp is climbing and boiling over while sitting idling, most likely a bad head gasket. This is a common symptom of a failed head gasket.

2. If the temp is climbing while driving down the road, even under light load it is most likely that your new aluminum 3 row rad does not have enough heat rejection capacity. Step up to a 4 row, brass and copper unit, and/or increase the frontal area of the rad as much as possible.

 

[Black dawg]

What conditions does it over heat under, and do you have a picture of your radiator and fans?

 

[Kyle akers]

It overheats under load driving around it climbs up a bit nothing crazy as soon as I give it a bunch of throttle it just climbs up real fast

 

[hesutton]

I would like to see the size of the radiator too.

Did you ever see bubbles in coolant while running?

Ever done a used oil analysis? Pretty to find coolant leaking into the oil on UOA. Your oil often won't be milky or have coolant pour out of the oil pan with a head gasket leak. Found a head gasket leak on my 6.9 before it showed symptoms with UOA years ago.

What are your EGT's running?

Heath

 

[FrozenMerc]

It overheats under load driving around it climbs up a bit nothing crazy as soon as I give it a bunch of throttle it just climbs up real fast

This statement right here tells me you don't have enough radiator. You need to reject more heat to the air. Increase fin density, frontal area, # of rows, only drive in the winter, etc.

 

[Fixnstuff]

Seems that I read a similar topic recently wherein an air lock in the cooling system was discussed. Usually it's in the heater core circuit. How well is the heater working?

OH BUT THIS: Is the radiator specified for a 1968 IH gas powered truck or a 6.9/7.3 IDI diesel? Curious: is that a pick-up or an old Travelall (spelling?) I remember those, 345 cid v8 and I had a box truck, (R-160 series bread truck, box separate from the cab but the back of the cab and front of the box were cut out for walk through - had bucket seats.) with a straight 6, completely rebuilt, and I liked that engine a lot! I think it was a 1959 or 60, maybe 63. I feel SO SAD about losing that truck and how I lost it and this is 52 years later!

The pressure relief cap on the IDI diesel radiator is 13 PSI.

Aside from other suggestions, also be reminded that we can't *SEE* your cooling system set up and you mention "electric fans." One good photo can help quite a bit for us to *see* what might be going on there.

I might suspect that the 'electric fans' are not moving enough volume of air. They might turn fast and push or pull with some velocity but not enough volume. The stock clutch fan has huge blades, has a tightly fitting shroud and moves a huge volume of air through the radiator. I've never heard anyone complain about a 6.9/7.3 specified 3 core aluminum radiator not exchanging heat well enough and it's a common replacement radiator.

Aluminum radiators are supposed to be very efficient radiators in terms of heat exchange. IS THIS AN AUTOMATIC OR MANUAL TRANSMISSION vehicle? (and if it's manual transmission you have a radiator for a manual transmission and not for an automatic?)

Where are the electric fans mounted (In front of or behind radiator?) and how big are they? From what kind of vehicle, or aftermarket? A PHOTO MIGHT HELP. You also need an adequate fan shroud for fan(s) to work efficiently, otherwise the fan(s) will pull air in from the sides (least resistance) instead of through the radiator, or push air out the sides if in front of radiator. There is a loss of efficiency without a good fan shroud and for 2 electric fans I think that ideally you would need one shroud that covers the whole radiator and fans that pull A LOT OF AIR.

Those are my thoughts. Sounds like an interesting project.