Good Solvent for removing Diesel Sludge?

[jamesdavis]

Re. Sea Foam, Thanks

[Lepke]

Don't run a diesel with kerosene in the engine oil. It may work for gas engines, but diesels can run on engine oil. Adding light fuel to the oil is asking for a runaway engine.
A good detergent oil along with some filter changes will eventually clean up the sludge. Obviously the oil pressure and filter has to be watch carefully.

[sailah]

If the seals are bad on your waterpump, you may have just found the reason for grey oil that happens repeatedly. Watch your coolant level and also look in the coolant overflow tank for black flecks of oil, classic sign of bad waterpump.

[Stu Jackson]

Originally Posted by jamesdavis

My boat is a '95 Catalina 30 with a Universal M-25XPAC diesel ...
BTW, found a rebuild kit for the Sherwood water pump...will try that before buying a new pump.
MAN! Boats are expensive!

Before you do so, please seriously consider switching to an Oberdorfer pump.

[jamesdavis]

I believe Oberdorfer was the original pump Catalina used on the C30 nd others; switched to the Sherwood because it has direct engine drive and perhaps other reasons. Can you elaborate why you think Oberdorfer pumps are superior? Tnx, Jim

[AndyEss]

Back in the late 70's and through the 80's I had VW diesel Rabbits. I occasionally ran an oil/diesel mixture through them to clean out sludge before a regular oil change - maybe once a year.
I'd go as high as 1:1, but never ran the engine with this mix for over 5 minutes, and never at more than idle. I'd drain this, and go on with a regular oil change, including changing the filter. Both cars ran for over 300k before I sold them.
Adding MMO per directions seems to be a good preventative policy also.

[MarkSF]

I've used the Sherwood and the Oberdorfer pumps on my Universal.

The Sherwood pumps a bit more water, and the impellers and rebuild parts are cheaper, but it is inferior in most other respects - durability, ease of changing impeller, and cost of purchase. The Sherwood pumps are also getting very expensive to replace with new.

However, neither of them is reliable and durable enough to not carry a spare, in my opinion. I speak as someone who had to cancel weekend cruising plans due to a leaking pump.

My suggestion is : buy an Oberdorfer N-202. Rebuild the Sherwood, keep it as a spare.

This is exactly what I did, except that I re-installed the Sherwood to test my rebuild, and ended up leaving it there. Thought I might as well see how long it lasts. About 100 hours so far.

I also have spare hose barb fittings pre-installed in the now spare Oberdorfer, so I don't waste time swapping those over.

[jamesdavis]

I looked up the Oberdorfer N-202 water pump, and yes, its cheaper, but when it comes to mounting, it does not appear like it is a direct fit to my Universal M-25XPA diesel engine. Curious which Universal you have and how you would accomplish the change-over?

[MarkSF]

Both pumps are a direct fit on my 5424. The Sherwood relies on two separate "L" shaped pieces, that bolt onto the engine and hold the pump on. The Oberdorfer does not need them, as the holes in the flange simply match the ones on the engine.

This is the Oberdorfer that fits mine : 5 bolt flange mount.

https://www.fisheriessupply.com/ober...pumps-n202m-15

In the description it says :

"The N202M pumps come with 2-hole mounting flanges and 5-hole mounting flanges. 2-hole models have a slotted drive shaft and an oil cup; 5-hole models have a drive shaft with a male tang."

5-hole is the one that fits my 5424. If you could post a picture of the output shaft on the engine, I should be able to confirm if it's the same as mine.

[Stu Jackson]

Originally Posted by jamesdavis

I believe Oberdorfer was the original pump Catalina used on the C30 nd others; switched to the Sherwood because it has direct engine drive and perhaps other reasons. Can you elaborate why you think Oberdorfer pumps are superior? Tnx, Jim

CNG & Sherwood Pump Dissection

[bustermaw]

Originally Posted by jamesdavis

Recently bought a '95 Catalina 30 with "black tar" in the poor M-25XPAC diesel!
A major lack of mechanical attention (laziness?) by the prior owner who had cunningly put a new oil filter on and said the oil didn't need changing! My fault for not checking.

I've changed the oil and filter 3 times running the engine for 1/2 hr each time but the oil is still a dark sludgy gray-black .

Is it wise to cut engine oil with kerosene (or diesel fuel) to help remove and clean the sludge from the engine, or is there a better solution?

If kerosene works, what ratio should be used and how long should the engine be run with this solution?

Thanks, Jim

I had to clean out my sump about a year ago when the water pump">raw water pump leaked salt water into the engine and the oil became emulsified . I couldn't suck it out so added 2 litres of kerosene and ran the engine until it warmed up .
It did a wonderful job of cleaning out the engine .
I changed the oil filter a couple of times and all was well .
The engine has since done 600 hrs and I can detect no ill effect .
Hope this helps .

[jamesdavis]

So BusterMaw, you did not cut the engine oil at all (!) but simply filled the sump with straight kerosene, ran the diesel until warm, just once, and all was well thereafter?
I have an idea the water pump leakage issue is what has happened to mine as well.

BTW, I called Catalina re. Oberdorfer vs. Sherwood raw water Pumps. Their technical guy explained the differences between the brands.

Sherwood advantages: greater pumping capacity and longer, more reliable service between rebuilds because there are sealed bearings within.
Disadvantage: more difficult to change impeller as bolts to gain access are on the backside of the front plate and more parts involved to rebuild.

There are 2 Oberdorfers with 1/2" fittings:
#1 must be modified to fit the engine block and must have smaller L pipes fitted. It is simpler to change the impeller and has sealed bearings but has less GPM throughput. Price is $320 +shpg.
#2-Oberdorfer fits the M-25XPA engine block without mod but has less throughput and uses a carbon bearing which cannot be easily changed (falls apart) and so the pump is basically pooched after it dies. Price is $436 +shpg. Perhaps a good backup and less than the $535 Sherwood.
Generally the Sherwood seems better built and has greater GPM throughput, however one must keep an eye in the tell-tale holes and rebuild it when they start to weep.
Thanks to all , Jiim

[a64pilot]

I would be very careful putting in a fuel type of solvent. The engine can run away if you do, maybe.
Plus the lubricity of kerosene is very poor and you could scar your bearing, crankshaft and especially your cam and lifters that way. I said could, not will, but the risk is not worth the benefit in my opinion.
Go with SeaFoam, Marvel Mystery oil or the old standby and use ATF, but don't use something that the engine will run on if it gets sucked into the intake manifold through the breather hose or past the rings.

[jamesdavis]

There seems to be as many opinions as answering sailors out there! Rather confusing to a neophyte seaman. I will go with the MMO and/or Sea Foam suggestions for now but only after the water pump is rebuilt, remounted and thereby eliminated as far as injecting raw sea water past the seals into the engine. Thanks, Jim

[jmschmidt]

Gasoline. I put a couple of cups of gasoline into my plastic jerry cans after filtering out the diesel to refill the boat's tank. The gasoline dissolves any diesel sludge, residue or grow that may be present. Use great care and dispose of the dirty gasoline in a responsible manner. My sail boat has only a 20 gallon diesel tank and is easily removable. I can clean the main tank this same way, after I put out my cigarette.