NHC-250 in a M939 vs a M809 truck

[steelsoldiers]

Can anyone tell me the differences between the set up on the 2 styles of engine? I know the 939 trucks use an air operated fan clutch and there is a linkage on the IP for the TV cable on the automatic transmission. Is the oil cooler different? Any intake or exhaust manifold differences? Anything internal such as crank balancing for the 809 flywheel vs. the 939 flex plate? Any IP calibration differences?

Thanks!!

 

[WillWagner]

The internals are gonna be the same. There might be a disc in the block loop of the cooling system so that when the stat is closed, the trans gets positive coolant flow. The coolers are the same. Intakes are the same, the exh is different. 809 exits straight down, the 939 sweeps toward the rear of the engine. I have parts books for both, I can scan the differences if you like. Cranks are the same.

 

[Andydieselpower]

We have a new fully dressed NHC 250 in the crate for the M900 series. As far as I can remember the fan height is different, The exhaust header is different. It's been 6-7 months since I've had the lid off of this engine so I don't recall a whole lot. I think it might have had an electric oil pump sensor instead of the mechanical gauge in the dash for the M809.

If you need pictures taken I could take some this weekend of the M900 series engine vs. one in our M809 series for a comparison for you.

What happened to your big truck project?

Andy

 

[steelsoldiers]

Thanks guys. I would like to see some pics of the 809 series engine. I remember the exhaust manifold now that you mention it. The 809 dumps straight down into the muffler.

Well, Andy, my big truck project turned into a HUGE truck project. Turns out the truck was submerged in saltwater up to the cab. The brakes were all rusted stuck, the cab was rusted badly, the linkages were rusted solid, the bedsides were salt welded in place. It looked great during a superficial inspection, but once I started turning some wrenches on it, it quickly went downhill. Bad, bad, bad... I am going to try and save some good parts off of it before it goes to the scrapper. Thankfully the owner let me wrench on it before I bought it. I am now selling off parts, trailers, etc... to raise currency for another 939 project

 

[area52]

So this would bolt into a 809 truck with a little modification? Does it put out more power?

 

[steelsoldiers]

Yes. It looks like you would have to swap exhaust manifolds, fan brackets, and maybe a sensor or two from your existing 809-series engine and everything else should work. The manuals list both engines at 250 HP.