392 non ic

4

47 dodge

New member
I have a 392 non ic. It was in my school bus/rv conversion with a MT-40 allison automatic. Problem was it kept blowing out the coolant on long grades even though the engine temp did not rise. Two pistons melted exposing the top ring. So I removed the engine and put a good running 345 in it's place with a 5 speed manual.

I know the block is differant from the IC version, however I am wondering if I change the coolant pipes to go to the block instead of the head will that noticably improve the cooling so I do not get hot spots and melt more pistons, or is this engine just not suited to long haul highway use?
 
It isn't just the block. The heads are the biggest difference. The non-IC engines, including all 266, 304 and 345 sizes, are made to work with the plumbing as originally designed. Changing stuff around won't work. I imagine that old bus with the non-IC 392 pulled heavy loads up steeps grades plenty of times before you got it. I'd be looking at what may have changed from those times to now for a possible cause.
 
I did suspect a head gasket, as you are correct it normally would be, however there was no leakage into the cylinders after sitting with pressure in the radiator overnight. Of course this is not proof of it not leaking. By the way changeing to antifreeze only, no water that did stop all radiator pucking.

What I really want to know is because IH changed the cooling there must have been some issue with cooling. I do not want tp put money and effort into rebuilding this engine only to have trouble again from cooling issues. Have others experianced cooling problems with the non IC 392 and what problems did it cause? And were the problems solveable? Has anyone tryed just changing the coolant tubes and seen how much difference it does or does not make. With the block and heads being different from the non ic perhaps it really is a lost cause, and these engines are not suited to long haul?
 
There were certainly enough reported complaints of cylinder hot spotting with the non-ic 392 engines in medium duty applications by 1971 to prompt the revamp around 1972. Anything that costly to the company wouldn't have been done just for grins. I suspect they realized that mounting warranty claims and lost sales from inaction would eventually cost them more, so they had to act. One thing you can't do is convert a non-IC into an IC via parts swaperoo. If it was as simple as changing the water tube plumbing, IH would have done that and called it good. Most of the members on this forum are running light duty vehicles, so the elephant in the room here is the obvious apples to oranges deal that most any comparison between a light duty and medium duty rig would invoke.
I've been a regular here for quite a few years and most of the discussions hereabouts related to these engines that I recall boil down to...differences between the two designs primarily for identification purposes...will putting 345 heads onto a 392, plus some strategically applied fairy dust, magically transform it into a neck-snapping, top fuel, dragster engine...and overheating issues of engines (of all sizes up to and including transplanted 392 IC) in Scouts. I've dealt with that last one myself. My Scout II cooling system, (marginal BTW for even a 304) simply wasn't up to snuff to handle the much larger engine. I finally cured my heat woes by bringing my entire cooling system up to snuff. This consisted of many system flushes, a new aluminum radiator, and a new Hayden Heavy Duty fan clutch. But again, this is in a Scout. The one kernel you might be able to take from it though, is ensuring that your entire cooling system package is as dead nuts perfect as it possibly can be.
 
Thank you. This sounds reasonable. I did replace the radiator with a new one from Griffen, and added an aux oil cooler for the trans.

So for now will just stick with the 345 I replaced the 392 with.
 
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