Oil in the bilge!!!
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=39124
Printed Date: October-07-2024 at 8:31am
Topic: Oil in the bilge!!!
Posted By: wetskier2000
Subject: Oil in the bilge!!!
Date Posted: June-27-2016 at 10:26pm
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1997 351 GT40, 1200 hours... After a day on the water, open engine cover to check bilge as I do nearly every outing and find OIL!! I carefully look over the entire engine as best I can with my fat head stuck in small places. No drips, apparent leaks, nothing... I mop up the bilge and it is mostly water with just a little oil... The dipstick says the engine is still full, the tranny says the same thing... Earlier that day, I was abusing the boat running it WOT at 6,000 RPMs for more than just a quick hammer and back down. It wasn't terribly long, maybe 30-60 seconds... The motor lost power, I yanked the throttle back and it ran fine the rest of the day... I rarely, if ever do this to the boat... Did I make it barf some oil somehow?? From where?? I thought maybe PCV and crankcase ventilation, but the only thing I find that looks like crankcase ventilation is the hose from the oil fill neck to the flame arrestor. The hose appeared to be clear and not oily at all inside. The flame arrestor was somewhat filthy on the outside but quite clean on the inside. I cleaned it and reinstalled... There were a couple drips on the top of the "flange" on the dipstick tube but I kind of wrote that off to a normal thing... Maybe not... Ideas, thoughts, dope slaps?? ------------- Current: 1997 Nautique Previous: 1987 Nautique 1964 American Skier |
Replies:
Posted By: Silver15
Date Posted: June-27-2016 at 10:41pm
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I'll be the first to say that 6k RPMs seems like a whole lot for a GT40 to be turning- perhaps your tach is incorrect. That being said, sometimes if a rear main seal on engine, or input shaft seal on transmission starts to leak, it is difficult to spot as it drips off the bottom of the bell-housing in a very difficult spot to see. ------------- 2000 Air/Sport 1978 T16 |
Posted By: tryathlete
Date Posted: June-28-2016 at 12:53am
| Any remote chance your oil filter rubber sealing ring might have stuck on the sealing surface when you pulled the old one off? (Sh)It happens. |
Posted By: DayTony
Date Posted: June-28-2016 at 1:22am
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first off can you explain the loss of power? was oil pressure and everything ok? you don't seem to concerned with that part just the oil in the bilge? If there are no apparent leaks than the only thing you can really do is run it and inspect it more. maybe get in there with a good flashlight while its on(not at 6000rpm though) I always have 1 or 2 of the white "oil only" pig mats floating around my bilge at any given time to sop up any oil, Maybe dry out the bilge and run it with a couple of those under it till you see drips. ------------- 1988 Barefoot nautique-454 |
Posted By: gun-driver
Date Posted: June-28-2016 at 1:42am
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1st what prop are you running being able to hit 6000rpm? 2nd the loss of power was the rev limiter. 3rd what color was the oil? Red = transmission brown = engine 4th if brown feel up under the bell housing and see if you get oil on your hand. If so rear seal (been there done that) |
Posted By: tryathlete
Date Posted: June-28-2016 at 1:50am
| Nice call on the rev limiter. What rpm does the GT40 cut out at? I'm curious. |
Posted By: 8122pbrainard
Date Posted: June-28-2016 at 7:21am
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How much oil was in the bilge? Keep in mind engines do leak. In a car or truck it isn't noticed like in a boat since it drips onto the ground. Besides color, see if you can get a piece of cardboard under the engine and look at it to see where the drips are coming from. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: wetskier2000
Date Posted: June-28-2016 at 12:03pm
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How much? At first I thought it was ALOT (and was horrified!), but when I mopped it up I realized it was mostly water. If I had to guess, I'd say no more than a teaspoon... maybe... Fortunately, there was very little water in the bilge since I had just repacked the prop shaft stuffing box a few days before. Definitely motor oil. Rev Limiter!..,. Good to know and I wondered if that was the case. Thanks! Stock prop... Although I have not had it redone in years.. I'm not sure how successful I'll be placing anything under the engine. It's very close to the hull... Maybe use the feeling around with my hand under the engine/BH after each outing.. I gotta wonder if bouncing off the rev limiter caused oil to burp out the dipstick tube... ------------- Current: 1997 Nautique Previous: 1987 Nautique 1964 American Skier |
Posted By: wetskier2000
Date Posted: June-28-2016 at 12:05pm
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1 other thing... there has never been any trace of oil in the bilge before. I keep the bilge pretty clean and I think I would have noticed. ------------- Current: 1997 Nautique Previous: 1987 Nautique 1964 American Skier |
Posted By: wetskier2000
Date Posted: June-29-2016 at 10:47pm
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first outing since the oil incident... I checked the BH before going out, it had what I'd describe as "oily moisture" but not so much as to be called "drips". Oil pan was dry. Checked it when we came back in after 3 runs each and still the same... ------------- Current: 1997 Nautique Previous: 1987 Nautique 1964 American Skier |
Posted By: gun-driver
Date Posted: June-30-2016 at 10:24am
| Keep on checking it I would bet the rear main is seeping a little. |
Posted By: wetskier2000
Date Posted: June-30-2016 at 11:05am
It very well could be... My current thoughts are the RMS or the sudden change in crankcase pressure from hitting the rev limiter forcing oil out somewhere. (there were drips on the dipstick tube). The look on my wife's face was not a smile after she asked "What's involved in changing the RMS?". and I answered "It's probably not too bad depending upon a 1 piece or 2 piece design, but if its leaking, the question becomes: What else should we be doing". I've done the upper exhaust manifold gaskets already, but not much else other than general maintenance. Thanks for all the help on this, guys! ------------- Current: 1997 Nautique Previous: 1987 Nautique 1964 American Skier |
gun-driver wrote:Posted By: gun-driver
Date Posted: June-30-2016 at 8:22pm
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I had to change my '95s rear main, not that bad of a job they are the 1 piece and can be purchased at a good auto parts store for 1/2 the cost that dealers charge. (same as a 5.8L truck seal) It is a seal and they do wear out with 1200 hrs I would imagine it could be starting to seep a little. You have one of two things going on, either your tach is reading incorrectly or your transmission is slipping because there is no way you would be able to spin the stock prop to 6 grand (Assuming it is the stock prop or similar to stock which was an OJ 14x16 I believe) |
Posted By: wetskier2000
Date Posted: June-30-2016 at 10:37pm
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Yup, it's a stock prop.. I would suspect the tach first. It seems right when skiing reading 34-3600 at 32 MPH and reads 800-ish at idle. But it doesn't go to zero when the engine is off. I will run some tests.. ------------- Current: 1997 Nautique Previous: 1987 Nautique 1964 American Skier |
Posted By: MrMcD
Date Posted: June-30-2016 at 11:11pm
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It sounds like you may have dodged the bullet this time. A little oil scare but maybe no damage at all. Rear Main Seals are either good or bad, they don't come and go. Sometimes if you have vibration, bad prop shaft or prop it can cause a good RMS to start leaking and keep leaking after the shaft is repaired. National makes a one piece Teflon rear main seal for the Ford that is a life of the engine product. Costs double a normal rear main seal but worth every penny. Teflon has special installation instructions so read up prior to using one. This same technology is used in all Diesel Engines for the long life capability. I would avoid the prolonged wide open throttle runs if you want your engine to last. No problem revving to red line, just don't keep it there for long. Glad you are running and all is OK. |
Posted By: gun-driver
Date Posted: July-01-2016 at 12:01am
800 at idle is to high it should be 600rpm. If it's idling at 800 it would be a ECT, ACT or the TP sensor fail that causes it to idle high according to the manual. |
Posted By: wetskier2000
Date Posted: July-10-2016 at 9:45am
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It appears the tach is the main suspect... While towing my wife the other day I noticed it was reading 4000 RPMs at 32 MPH. I've seen other odd behavior also... Any clues on where to begin diagnosing the tach? ------------- Current: 1997 Nautique Previous: 1987 Nautique 1964 American Skier |
Posted By: gun-driver
Date Posted: July-10-2016 at 5:32pm
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There's really not a whole lot to check, gray wire out of coil connector goes direct to the tach. Check connections on tach are clean and ground is good. The only other thing is there's a diode somewhere (don't know where) in between the coil and the tach it converts the signal to a marine tach |