Perkins 4.154 Pouring oil from breather tube

[Toomuchboattime]

Long time reader of cruisers forum. Glad to be a member now!

I've been renovating a 1975 Formosa 41, with decent luck so far. She's equipped with a Perkins 4.154 45 hp diesel. I fitted the engine with a new exhaust system, new hoses, had the injectors rebuilt and for the last few months, she's run like a champ. Motored 5 hours pretty recently with no issues. Went to start the motor yesterday and she was hard to start, which is not usually an issue. Turned the motor over in 10 second increments and it seemed like maybe 1 of the cylindars was firing. Ran really rough then died. Opened the engine compartment to find it covered in oil. Lots of oil. Took the cap off the air intake and ran the engine for a second... long enough to see oil absolutely spout, I mean pour, out of the breather tube. I haven't changed the oil recently, so no overfilling there. Checked the oil dipstick and it was covered in oil halfway up the stick. Pretty sure that's not good. No foam or white color to the oil- as black as can be which surprised me. Any ideas here? At first I thought maybe the intercooler went and antifreeze made it into the oil pan raising the oil level? Blown head gasket? Any advice is greatly appreciated!

[Compass790]

Welcome to the forum.
First off my question may be silly as I dont know your engine model but does it have an engine mounted mechanical lift pump? Is the oil thin & smelling of diesel?
If yes to both of those you may have a broken fuel pump diaphragm. That would be my first guess but others familiar with your engine may chime in with other possibilities

[Jason Flare]

When you say the oil was halfway up the dipstick does that mean you wiped the stick and the oil level was high?

If so you have either water at the bottom of your oil pan or, as Compass790 said, diesel mixed in with your oil.

I would loosen the drain plug on the oil pan and see if you get oil or water.

[Toomuchboattime]

Thanks for the warm welcome! It does have a mechanical lift pump. Forgive my lack of understanding- how would the fuel make it into the oil pan if the diaphragm gave out? Thanks for the help!

[Toomuchboattime]

Great idea. I'll give it a check! The oil on the dipstick does not seem thin, rather thick actually. Gave it a wipe and it is still high.

[MarkSF]

We should not dismiss the possibility that the engine was overfilled with oil. That explains all the symptoms. Is it possible that it could have got overfilled?


Do you remember a time recently when the dipstick read the correct reading?


I think at this point your best option is to change the oil, make sure the level is correct, and see if this problem repeats itself.

[Compass790]

Originally Posted by Toomuchboattime

Thanks for the warm welcome! It does have a mechanical lift pump. Forgive my lack of understanding- how would the fuel make it into the oil pan if the diaphragm gave out? Thanks for the help!

I'm reluctant to say as I dont know how your particular engine is setup but normally the diaphragm is the only thing that separates the fuel from the crankcase. There is an actuating lever on the pump that rides on a cam inside the block. I'm not sure how your pump is driven though.
Best to wait for someone who has or is familiar with your engine to chime in.

But yes overfilling the oil is the first thing to rule out.


You could search for oldcal46 & PM him as he rebuilds Perkins IIRC

[Toomuchboattime]

Originally Posted by MarkSF

We should not dismiss the possibility that the engine was overfilled with oil. That explains all the symptoms. Is it possible that it could have got overfilled?


Do you remember a time recently when the dipstick read the correct reading?


I think at this point your best option is to change the oil, make sure the level is correct, and see if this problem repeats itself.

I suppose it's possible, but having used the boat for many hours prior, and having added no oil, I'd be surprised if that were the case. Still, a fresh oil change is a good idea and smart to rule out the possibility! Thanks!

[Toomuchboattime]

Originally Posted by Compass790

I'm reluctant to say as I dont know how your particular engine is setup but normally the diaphragm is the only thing that separates the fuel from the crankcase. There is an actuating lever on the pump that rides on a cam inside the block. I'm not sure how your pump is driven though.
Best to wait for someone who has or is familiar with your engine to chime in.

But yes overfilling the oil is the first thing to rule out.


You could search for oldcal46 & PM him as he rebuilds Perkins IIRC

Ahh that makes total sense. i do recall the lifter pump going straight into the block, as I'd removed it to have it's pressure checked. Definitely a possibility. I'll drain the oil and if there's any sign of diesel, I'd guess you're correct! Thanks!

[Compass790]

Originally Posted by Toomuchboattime

Ahh that makes total sense. i do recall the lifter pump going straight into the block, as I'd removed it to have it's pressure checked. Definitely a possibility. I'll drain the oil and if there's any sign of diesel, I'd guess you're correct! Thanks!

It may not be the lift pump leaking as you said the oil appeared to be thick so dont get too excited yet as you would expect it to be thin if getting diluted with diesel.

I did look up your engine & it does have the type of lift pump that can leak into the sump.
Also it may be that the injection pump could be leaking but again I'm not familiar with them.

It doesnt sound like the coolants getting in either or you would expect it to be milky.

Here is the link to the service manual if you dont have one.


https://www.kp44.org/ftp/Perkins_4-154_Shop_Manual.pdf


Good luck with finding the problem.

[mvweebles]

I'm a decent shade tree mechanic (whatever the marine equivalent is), but no expert. My mind went somewhere else when I read the OPs description. He described engine not firing on all cylinders; and a lot of oil spouting out of the breather. If oil was spraying out vs overflow, that speaks to excess crankcase pressure - blow-by usually caused by worn or broken rings. But that should be accompanied by exhaust smoke of unburned oil (blue) or fuel (white).

Checking for diesel in fuel is a good first step. You may also want to adjust the valves and make sure all the cylinders have opportunity to make compression. You may also want to try a simple/crude blow-by test to check for excess crankcase pressure. It's hard to know if you haven't done it on a healthy engine, but remove the oil fill cap on top of valve cover with engine running. There really should not be any excess pressure - a paper towel should not be whisked away quickly with engine at idle speed.

Good luck

Peter

[oldcal46skipper]

1-Check the mechanical fuel transfer pump diapragm. They do wear and leak fuel into the oil pan overfilling the crankcase and blowing oil as you described.
2-The amount of oil you describe suggests this issue which can be fairly common 0n 4.154's
3-Parts are readily available from TransAtlantic Diesel & others. I am parting out 3 4.154s for good used parts.

[mvweebles]

Originally Posted by oldcal46skipper

1-Check the mechanical fuel transfer pump diapragm. They do wear and leak fuel into the oil pan overfilling the crankcase and blowing oil as you described.
2-The amount of oil you describe suggests this issue which can be fairly common 0n 4.154's
3-Parts are readily available from TransAtlantic Diesel & others. I am parting out 3 4.154s for good used parts.

BTW - I recently replaced my lift pump on my 4.236 which is probably the same as on the 4.154. Purchased via TAD as Oldcal suggests and was not very expensive - maybe $100 if I remember. I replaced all the pumps - raw water, coolant circulation, and lift pump - for something like $400. Just didn't make sense to try to rebuild given the low cost.

Would be great if lift pump is the issue. I look forward to an update.

Peter

[Jack C]

Originally Posted by mvweebles

BTW - I recently replaced my lift pump on my 4.236 which is probably the same as on the 4.154. Purchased via TAD as Oldcal suggests and was not very expensive - maybe $100 if I remember. I replaced all the pumps - raw water, coolant circulation, and lift pump - for something like $400. Just didn't make sense to try to rebuild given the low cost.

Would be great if lift pump is the issue. I look forward to an update.

Peter

Peter, Where did you find a raw water pump for a 4236 for less than $600? I rebuilt mine because of the high cost of this pump. The mechanical seal alone was more than $50. The fresh water pump was about $70 as it is not a boat specific part.

[Jack C]

Looking more carefully at what you can see will help find the actual problem with the least effort.
1. Is the oil milky or has water droplets? If yes, coolant or raw water. Your engine may have an oil cooler? My 4236 does. A hole in the oil cooler heat exchanger is more common than a head gasket problem.
2. Is the oil thin and smells of diesel. If yes, hole in diaphragm in low pressure pump is likely especially if oil level is high after spurting.
3. What is the present oil level after spurting? If no liquid is coming in then it may be crankcase pressure problem.