Good Solvent for removing Diesel Sludge?

[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

[DeborahLee]

Try some marvel mystery oil. About a 1\2 qt to 4 qts oil. Over 4 qts add 1 qt.

[Cheechako]

If it is that gummy and coated inside I doubt anything will really remove it. In fact, you may just loosen it up causing more potential issues than leaving it alone. It should have cleaned up with one oil change. It almost sounds like the PO was using low detergent old school oil. I have seen gas engines with less than 35k miles with about 1/16-1/8" of black buildup inside the engine. In this case it was old school oil and never being run good and hot, short trips and the motor never fully warmed up.
You can see how coated it is by removing the rocker cover and see how thick it is in there. If the engine is good, do yourself a favor this winter and remove it and clean it up good.... inside the covers, remove the pan and clean it up etc....or just ignore it I suppose.


Getting black and sludgy in a half hour just doesn't add up unless it's real bad. Are you sure you are getting all the old oil out?

[model 10]

Originally Posted by Cheechako

tc....or just ignore it I suppose.
Getting black and sludgy in a half hour just doesn't add up unless it's real bad. Are you sure you are getting all the old oil out?

We had a rule to not switch to detergent oil if the engine had been running straight oil for a long time. Cutting loose all that sludge can clog filters etc. An old trick is to put your hand on the filter to see if it's hot. If not it's clogged.

My old perkins would turn good oil black pretty quick. Turns out it had some stuck oil rings.

[leboyd]

Originally Posted by jamesdavis

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?

This is not unheard of and done a lot on old farm equipment. Generally, it's done 5/1, oil/diesel and then run for about 10 minutes, drain, refill with oil. With the newer oils with detergent and regular oil changes, it shouldn't be necessary, but it shouldn't hurt the engine to try. You're biggest issue as mentioned is the sludge getting into places you don't want it - but then you already have that issue. You can look up this practice on Google.

[a64pilot]

You can cut the oil with Diesel, kerosene, mineral spirits, just about any solvent.
If you do this I would go to a thicker oil, say a straight weight 40W to keep pressure up.
However I would say go with the Marvel Mystery oil myself, and run 10 hours, change it and add MMO to the next, run 25, then 50 hours. By then you should be able to go normal oil change intervals.
This isn't your first Diesel is it? Cause a good running Diesel will turn oil to a pure black in a short time, that is just the Diesel soot is all.

Nothing wrong with running MMO in oil either, I did in my airplane and did so every oil change, I thought it hooey until I saw more than one 1340 with sticking valves, no longer have sticking valves with MMO. You have to see it to believe it.

[a64pilot]

The sludgy grey color you speak of is worrisome, cause that sounds just like water getting into the oil to me.

[Jim Cate]

Originally Posted by a64pilot

The sludgy grey color you speak of is worrisome, cause that sounds just like water getting into the oil to me.

Yeah, me too! When it's grey rather than deep black, it sounds like water emulsion. So, OP, put some of the grey oil in a glass jar an let it sit for a few hours in a warmish place. IF it is water, it should separate to some extent and form a clear layer at t he bottom of the jar.

Jim

[DocRox]

All of the above is good advice.
Get your oil analyzed, twenty bucks ish and it will give you a good idea of your engine condition, but you will need some hours on a fresh oil change to get a good indication.
Changing filters more often than your oil might help too.
You may need to ad a bypass oil filtration system to catch the sludge as it cleans up.
It may also indicate that the motor has been overheated at some point.

[jamesdavis]

Thanks all for the sage advice.
I will try the MMO. We had the water pump off today and the seals did not look good. Gray oil just where the shaft connected to the engine drive, so we are going to spent ~$550 for a new water pump. Perhaps water seeping past water seal into the engine.
The PO changed the oil last in 2015!

[Igwet]

Sea Foam - follow instructions and you will be fine.

[jamesdavis]

Thought of Sea Foam but thought that was a gas treatment(?) I pour it into gas tank on my Toyota camry...

[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!

[a64pilot]

Originally Posted by jamesdavis

BTW, found a rebuild kit for the Sherwood water pump...will try that before buying a new pump.
MAN! Boats are expensive!

Yes they can be, when you get that kit, be sure to write down the part numbers of the seals and bearings, its very likely that you can buy them at a fraction of the kit cost.
Also I think there is a Catalina owners group that may well be worth looking into

[Igwet]

Follow directions can pour 1 oz per qt into the oil, run it hard and you might have to change the oil a few times afterwards but it will prob clean out all sludge. I have done this on many gas and diesel engines.. google it and there are youtube vids showing how to do it .