Perkins 4-108 - Fuel in Oil

[Stirfryd]

Hi All. Some not-so-good discoveries today. After I splashed the boat after a year on the hard, I brought her around to the marina. Noticed some low oil Pressure when at idle. Checked the oil that I had just changed and was surprised to find it a qt and a half high. Thought I had goofed. Drained it to and appropriate level. Have run the engine about and hour since then. Again low pressure. Checked oil. 4 qts. high! Now it is very thin, but no sign of water at all. So it appears that it is fuel. I know the next question is "how much time is on the motor?". about 3500 well broken in hours. I am the eternal pessimist when it comes to mechanical things. What say you? Need to replace rings perhaps? someone suggested that since the engine sat for a year that the rings might not be seated anymore and that some upper cylinder lube like Marvel MO might be worth a try. Any diesel Mechanics want to take a stab at it?

Thanks mates,

Stirfry

[Blue Stocking]

What type of engine? If this came on suddenly, unlikely it is rings. Could be fuel pump diaphram leaking, or a number of things.

[marcro]

Check the fuel pump for a leaking diaphram, if your lucky that will be the problem. If not it is likely to be the cup seals on the injection pump, these seals are found on the inside of the injection pump where the drive shaft enters the pump. When these seals fail diesel fuel finds its way to the sump via the timing cover. This is a job for a specialist as these seals require the pump to be stripped in order to replace.

I have just dealt with this as a problem on my own yacht.

M

[Stirfryd]

Sorry, engine is a Perkins 4-108.

[swabbmob]

I had a similar issue and we looked at the seals on the fuel pump, but determiined an injector tip was blown out by water in the fuel. Sounds like you've caught it early.

[svHyLyte]

I think Marco put his finger on the issue and I would be most suspicious of the fuel pump as the amoumt of leakage you describe in the relavtively short time period would seem to point at the fuel pump diaphram rather than the injection pump. Fortunately the pump is relatively inexpensive and easily changed.

Have you by any chance run any "Bio-Diesel" or the like through you system at any point?

[Jesse]

Marcro has pointed out the most likely suspect and it is also the least expensive to repair or replace. How's your luck been lately?

[Maddog]

I just replaced the lift pump on my 4-107. $58 and 2 bolts later all is good in under a 1/2 hour. Start there. I was lucky, my leak was coming out the side and clearly visible while the engine was running.

[Stirfryd]

I had a spare lift pump onboard. Replaced it. Changed oil. Nice clean crankcase now. Ran at idle for an hour. Checked oil qty. Normal! The real test though, was operating under a load. Put it in gear in the slip and ran the rpm up to about 1500 for a few minutes. Unfortunately the level on the dip stick is up about a quarter of a quart. So it seems that the oil quantity increases when the engine is working. The local 4-108 Guru didn't survive the economic turndown, so I'm in the process of trying to find a mechanic. In the meantime, I talked to a Perkins service center in Jacksonville. The service manager assured me that the high pressure pump needs rebuilding and was the likely source of the problem. $600-700. I'm wondering if I should investigate the injectors first? Also does anyone have experience pulling the injector pump? I Have the manual and enough mechanical experience to get me into trouble.

[svHyLyte]

Stirfryd--

I'm sorry to learn that your fuel pump was not the culpret. Pulling the injection pump can be a job as, depending upon your access, one may have to entirely remove the heat exchanger from the engine and several unique tools are required although you may be able to cobble those up. If you do not have the shop manual for the engine, I believe Gordon May, the Guru of search on this forum, can direct you to a down-loadable on-line version.

Good luck!

[slacker]

Getting the injector pump off your particular boat is a bit of a challenge. Its much easier if you remove the sink unit. Its not as bad as it sounds. there are about 20 screws that hold it down to the cabin sole. It too me about 2 hours to do it the first time. Once its out of the way you have access to the entire front of the motor. You will have to remove the exhaust manifold to get to everything and remember to set the engine to TDC on # 1 piston. Be sure to look for a timing mark on the pump and block. If you cant find it just use a punch and give a wack in a spot where the pump body bolts up to the block. Once you remove the pump do not for any reason rotate the crankshaft. Take the pump to an injector shop and they will probably have it back in a couple of days. As long as you are there pull the injectors and have them done. Expect to pay about $60.00 for a complete rebuild of each injector and about $500.00 for the pump. Be sure to ask them to replace the nozzles on the injectors. The injector shop will set the pump to TDC so when you bolt it back up everything will be in time. If you need some parts I can recommend TransAtlantic Diesel.

Good Luck

[Maddog]

Salcker has it right. I just did this last fall. A couple of points from my experiece.

1:I did not set the engine at TDC. As long as you don't rotate the engine your timing will be fine.

2: The shaft on the fuel pump is splined and keyed, it is impossible (?) to install it wrong. This will insure the timing is correct. Match up the timing marks on the pump to the block.

3: Perkins in their infinite wisdom attaches the pump with 2 bolts and one hex-socket bolt on the top inside. Why? ask them. Just be prepared for it. I got some long hex drivers from harbor freight that did the job.

I was able to do mine without removeing the intercooler, watertank or exhaust manifold. I was working upside down and backwards with a mirror to check the position of the key and working the shaft back and forth until I got the right rotation. It took me about 2 hours to get it working this way. When the pump shaft finally slid into place it was more gratifying than the first time with that chick back in high school, (Moderator: Please don't delete my post, ban me from posting or lecture me for the crude sexual reference. All I can say is that I worked harder on that pump, than I did on Leslie 30 years ago). After the hard lines were reinstalled and bled, that thing started right up on the first try. One of the longer but better evenings I had in a long time.

[Stirfryd]

Maddog,

Your analogy is quite inspiring. I'm on my way now with the tool bag. But before I go, I want to throw this out for a reply: based on my aforementioned symptoms and actions so far, is removing the injector pump the next most logical path to take? I also should have mentioned that while watching the motor idle yesterday and inspecting the whole rig for leaks, I noted a leak on the injector pump, One drip of fuel every 30 secs. It's dripping on the high pressure line for the No. 1 cylinder (the fitting on the bottom. This fitting was not loose and I was afraid to torque it to much. This did not stop the leak and while I can't find the source, it seems to be coming from the backside of the pump and perhaps NOT that fitting (it happens to be the low point on the whole rig).

Ready for the backseat!

Stirfryd

[Maddog]

I had my leak in the same spot. Go for the rebuild. When I took the pump off, the shaft and surrounding area was fouled with black engine oil. My mechanic said an internal seal had failed and I was burning a small bit of oil with the fuel. After the rebuild was installed and running a very slight smoke problem in the exhaust went away and the perkins ran smoother. If the leak is from one of the hardlines, you could try replacing the rubber olive, I have my doubts about that. I think you have a worn seal and it is dripping from the low point on the pump. A flashlight and a mirror would help you determine that. I'm told and I belive that the high pressure fuel pump is not a self-service item. Shop it at TAD or S&W Diesle in So. Cal. Mine was a little over $500 + Tax. like Slacker says, Do your injectors at the same time.

I have noticed that by fixing one problem, the next weakest link is exposed. The gasket/diaphram on my lift pump began leaking about 20 engine hrs after I replace the HPFP. It almost makes sense to replace whole systems at one time. I'm sure that both my pumps were at least 20 years old.

For me, next is cooling -- or -- maybe I'll spend the afternoon in my office remembering Leslie and wishing I knew more about deisle mechanics and high pressure pumps when I was with her last.

[donradcliffe]

Maddog has it right--its the seals in the injector pump, which can be taken off by removing two bolts and one hex--the hex will take a special long tool, and you will be cursing the engine designer by the time you are done. Be sure to mark the exact alignment of the pump before you loosen things up. My pump was leaking externally more than internally, but the rebuild will fix everything.