Which 300 series engines can replace the 4219T?

My JD 410B Turbo backhoe got coolant in the oil due to a head gasket failure, and spun several rod and two main bearings before we caught it. The crank was salvageable but the spun main bearing bores in the block were badly worn, to the point that my machine shop can't salvage the block. I've been searching for another 4219 block with no luck, except for cores of unknown status.
I've located a complete running engine from a Hydro Ax 221 feller buncher. It has no Engine ID plate, it has a block ID of R90170 and injection pump ID of DB44275002.
I've sent many hours trying to research these numbers to assess whether they could replace my 4219T. I'm pretty sure the Hydro Ax 221 only came with a 4239T but the injector pump seems to indicate this is a 4276T 115 hp, way more than the 65 hp of the 4219T. I don't think the power ratings are horribly incompatible, but I'm most interested in whether this will bolt in and function in my 410B.
- Do the block and injector pump ID's reveal this is a 4239T, or 4276T?
- If these aren't definitive, is there any other external marking I can use to ID the engine?
- Am I on the right track? The only visible external difference I can see from the pics is a much larger oil cooler, as the 4219 had the oil filter inverted and mounted to a small 4 x 4 inch coolant heat ex changer - the replacement engine has a much larger cooler and the filter is mounted horizontally, above and to the rear of the fuel pump.
- The JD parts catalog references short and long noses on these crankshafts. How can I tell the difference externally, and would it matter? The 410B hydraulic pump is directly driven by the front of the crank, but I don't know if anything was similarly driven on the Hydro Ax - the front pulley looks like there was something bolted to it's face similar to the 4219T but I'm not sure this is meaningful, or whether it would make it compatible with the 410B hydro pump.
I welcome any inputs, experience, or guidance - the local JD dealer service dept has been absolutely no help in trying to assess compatibility of any replacement engines. Thanks in advance -

All pics are of the replacement /unknown engine.


















This post was edited by sovste22 on 01/06/2023 at 06:37 pm.

Welcome to this forum
Your present crankshaft appears also to fit 3.9L(4239) engine block. I would think any complete JD 300 series 4 cylinder complete engine should fit your 410B. There are many applications presently that utilize a 4276(4.5L) 4 cylinder engines that will fit your 410B.

R90170 is a block number that shows up for a 4276T in a 450E crawler. Visually the engine in your pictures looks like the 4276T in my machine. Coverting the casting number to a replacement block part number it shows up in 4039 and 4045 series engines as well. Searching Hydro Ax 221 there is info that at least some used the 4276T engine.

The engine ID tag should have been mounted on the flat area below the oil filter, but it appears to be missing. No ID tag could mean this is a replacement block.

Thanks, Jim - this confirms what I found during my searches, but I didn't realize the Hydro Ax 221 might have the 4276T....that old model and related info have been extremely hard to find using my search engines. I had been hoping this was a 4239T simply due to it being closer to my 4219's power rating - but the huge power gain from the 4276T would be hard to refuse.

I noticed the block casting bulges visible on this 4276T at the rod journals - not sure if this is a non-structural block, or maybe just bumped out clear the longer stroke - the price is right, so I'm not too concerned if it isn't the ideal replacement for my hoe.

Thanks for the welcome! I've been a lurker over the 15 years I've owned this 410B - great forum with great people.

Glad to hear the form/fit should be OK with the 4276, or 4239 if I can find one. Other than needing to change the muffler, I suppose I could even toss a non-turbo engine in there just to get it digging again. To be honest, when I tore the 4219T apart to find the head gasket leak (never found it - altho I did have combustion gas and bubbles in the radiator), I found the turbo was pretty much non functional anyway - too much play and drag for it to really spool up - I never ever heard it whine/whistle under load, or even spin down after shutdown.

(quoted from post at 17:08:37 01/07/23) Thanks for the welcome! I've been a lurker over the 15 years I've owned this 410B - great forum with great people.

Glad to hear the form/fit should be OK with the 4276, or 4239 if I can find one. Other than needing to change the muffler, I suppose I could even toss a non-turbo engine in there just to get it digging again. To be honest, when I tore the 4219T apart to find the head gasket leak (never found it - altho I did have combustion gas and bubbles in the radiator), I found the turbo was pretty much non functional anyway - too much play and drag for it to really spool up - I never ever heard it whine/whistle under load, or even spin down after shutdown.

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There was no problem with the head gasket . The problem is cavitated wet sleeves . Somebody did not change or replenish the corrosion inhibiter in the coolant .
There is a slight chance that the sleeves are ok but the O'rings have deteriated.
Happens all the time but always seems to be a surprise .

Wow - that is right on! All four sleeves had a broken upper o-ring and cavitation erosion on the exterior of the sleeves, progressing in a v shape upward from each o-ring break. Yes, I never added corrosion inhibitor in the 15 years that I've owned it.
But I don't fully understand how the o-ring breaks resulted in combustion gas pulses into the radiator, or coolant in the cylinders? That still baffles me a bit.

So my 4045T arrived pretty much intact, and I was surprised to find two stickers on the valve cover indicating the motor is a JD-authorized RPO JD reman. Apparently RPO services timber industry equipment in SoCal and AZ, where this engine came from, reportedly from a HydroAx feller buncher.
I cut open the oil filter and found no debris. Pulled the deep, cast pan and it is clean, but at the bottom was a 1 brass Dorman freeze plug - it has no witness marks from being installed or beaten about crank and pan, it still look new. I suspect the reman block used the plug to seal off an oil cooler plumbing hole in the block, and the installer knocked the plug down into the block when retrofitting the old external parts?
Otherwise all gear backlash is under spec, same with crank end play. Rod side gaps in spec. I don't plan to pull rod or main caps as I don't want to replace the bolts. Due to signs of minor seeps, I'm installing new front and rear JD crank seals.
The turbo is toast, with most of the exhaust turbine blades cut down by some debris, probably damaged when the original HydroAx engine coughed up a valve or similar. I plan to just install my rebuilt 4219T turbo in it's place for now - if all checks out on startup I'll replace with the proper 4045T spec turbo.
I appreciate the forum's guidance and advice in moving forward with this 4045T - I believe it to be a great buy and solution to my bad 4219 block. Will post update after install.