Leaky oil manifold Universal M25

Stu Jackson · Nov 11, 2012

Scott, I'm somewhat confused. The oil pressure is at the front of the engine, the transmission is at the rear. I'm also confused about the phrase "oil manifold." Can you be more specific. We have tons of M25 engine information on our C34 website (http://www.c34.org/wiki/index.php?title=Diesel_Engine), feel free to poke around, but I don't recall that phrase.

anchorclanker · Nov 11, 2012

A picture might be helpful?

Maine Sail · Nov 12, 2012

Sefuller said:
Here are a couple of photos - one showing the oil manifold - straddling the heat exchanger brackets on top of the bell housing, and another photo showing an exploded diagram of the heat exchanger portion of the M25 parts schematic. Part #20 is the oil manifold. There is a rubber hose from somewhere around the alternator that seems to supply the manifold - I'm wondering if that's what is leaking. As far as I can tell the only thing the manifold is doing is holding the oil pressure switch. I wonder if the purpose of the manifold is to provide easier access to the switch?

https://www.dropbox.com/sh/3y73x3mm4m3go57/vJHVcgYOFW

What did you use to re-seal the threaded fittings into the oil manifold? Normally an oil resistant pipe dope is what you'd want to use. Best to fully clean it 100% then run the motor and wipe a white clean Q-Tip around each fitting to try and locate which one is leaking. Most of the oil senders on those motors go directly into the block and I don't think they used the manifold for very long in production.

Me and Boo · Nov 16, 2012

My 1984 M25 has one. I will be looking mine over now for signs of leaks.

anchorclanker · Nov 16, 2012

What MS is saying, is you can probably re-locate the sender directly to the block, where the oil line is coming from, and delete all the other parts, manifold block #20, etc.. The less parts you have the less number of points for potential leaks are possible.

After removing the line at the engine block, if you cant screw the current sender into the block directly, you can either get a different sender with the correct size thread (NAPA, etc..), which is the preferred way, or use an adapter, which is "ok". Either would be far better than the current arrangement.

Stu Jackson · Nov 16, 2012

Now I get it. Thanks for the backup info.

My M25 doesn't have that #20, but we don't have an oil pressure gauge, either. IIRC, the oil pressure sender is on the rear port side, low down on the block.

While shown in the blow up you provided, I suggest that that is probably the very worst place for anything with connections on it. Why? The vibration at the plate that holds the HX on is large. I've had reports of broken plates, and mine did, too. http://c34.org/bbs/index.php/topic,6920.msg46294.html#msg46294

Consider relocating it. Or eliminating it altogether and go from the block to the gauge.

Good luck.

Maine Sail · Nov 17, 2012

anchorclanker said:
What MS is saying, is you can probably re-locate the sender directly to the block, where the oil line is coming from, and delete all the other parts, manifold block #20, etc.. The less parts you have the less number of points for potential leaks are possible.

After removing the line at the engine block, if you cant screw the current sender into the block directly, you can either get a different sender with the correct size thread (NAPA, etc..), which is the preferred way, or use an adapter, which is "ok". Either would be far better than the current arrangement.

If I am not mistaken the Kubota blocks are tapped JIS (Japanese thread standards) or basically BSPT (tapered) or BSPP (straight threads) for oil senders so you'd likely need a BSPT to NPT adapter or BSPP to NPT I can't recall if the block is tapped parallel threads or tapered...

I have used ones similar to this before..

1/8" BSPT to 1/8" NPT

1/8" BSPP to 1/8" NPT