Oil Leaking
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=1119
Printed Date: November-22-2024 at 9:56am
Topic: Oil Leaking
Posted By: SkiLew
Subject: Oil Leaking
Date Posted: January-11-2005 at 11:45am
| I have an older inboard boat with a PCM 351 ford engine with about 800 hrs on it. I noticed the other day that oil is collecting on the top of my intake manifold right below the carburetor but I cannot tell where it is coming from. Could it be blowing by from somewhere or is it leaking? |
Replies:
Posted By: 79nautique
Date Posted: January-11-2005 at 12:14pm
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Most likely it is a front seal in the timing cover that is bad and the pulleys and belts are throwing the oil around and it is collecting on top of the intake. Take a look at the underside of the engine cover and look for signs of oil above where the pulleys are. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: AWhite70
Date Posted: January-11-2005 at 1:31pm
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I had a similar thing happen on my '79 Nautique before I rebuilt the engine. Oil would pool in the crevices of the intake manifold behind the carb. It definitely wasn't coming from the front cover. After I rebuilt the engine it stopped doing it. I never did find the source of the leak but I have two theories:
1. The valve covers were leaking and oil was collecting on the intake manifold-easy and cheap to fix. 2. My engine had multiple scuffed cylinders (i.e. high blowby). I suspect a lot of oil was coming through the breather tube to the base of the carb. This oil would then drip out of the tube and pool on top of the manifold.-not so easy and very expensive to fix. For your sake I hope it's number 1. |
Posted By: Tim D
Date Posted: January-11-2005 at 2:54pm
|
If it's in front of the carburetor check the distributor, it has a donut type gasket at the top, if the oil is behind the carburetor, check the pcv hose and and check to see if the pcv will rattle when you shake it. ------------- Tim D |
Posted By: SkiLew
Date Posted: January-11-2005 at 3:15pm
| Oil is behind the carburetor but the PCV appears to be operational (will rattle). Any other thoughts. |
Posted By: 79nautique
Date Posted: January-11-2005 at 6:15pm
|
Look at the vent hose (if yours has one) as well as the hose from the pvc valve and remove them and look for oil residue inside of the line if there is then you have a lot of blowby also look at the vavle covers and make sure it's not one of them, usually if the valve covers are leaking then it will run down the side of the block and not on to the intake, it's a gravity thing you see, it's hard for the oil to go up and over, it usually will flow down and around things.
Also check the rubber grommet where the PVC valve goes into the valve cover if it is hard or cracked replace it. Also look inside of the flame arrestor for oil, again another sign of blowby ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: workky
Date Posted: January-16-2005 at 11:54am
| Gravity,Huuum.Thats why the front seal was the first thing on my list as to why I would have oil on my manifold |
Posted By: 79nautique
Date Posted: January-17-2005 at 12:22pm
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Have you ever hurd of an oil slinger? that's what happens when the oil leaks out of the front seal on to the back of the harmonic balancer then gets thrown or slung everywhere then hits the underside of the engine cover then gravity takes over and deposite it on the top side of the manifold. Don't beleive me pour water on to the pullys or harmonic balancer while the engine is running and watch. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: SkiLew
Date Posted: January-17-2005 at 3:53pm
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79nautique:
Thanks for the info. I am familiar with what an oil slinger or sometimes referred to as an oil flinger is. The issue is that the underside of my motor cover does not show any signs of oil so oil is not getting to the motor cover and then leaking down. Oil is coming from some other source. |
Posted By: 77stang
Date Posted: January-17-2005 at 4:04pm
| for whatever reason, i had oil seeping from the intake manifold bolts a while back. to fix i re-torque them to specs in the factory designated order. this stoped the majority of the problem |
Posted By: David F
Date Posted: January-17-2005 at 5:19pm
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I vote for the source of the oil being the vent hose. Atomized oil in this line is normal and can collect (condense) in the spart arrestor in sufficient quantities to run down the outside of the carb and collect on the intake manifold.
Now, this can happen without excessive blowby, but can be agrevated by a dirty oil seperator. The valve cover must be removed to clean the seperator. |
Posted By: jbja
Date Posted: February-01-2005 at 12:49am
| I had the same problem. Put bolt thread sealer on intake bolts and retorque.Fords are notorius for this because of the way that the bolts enter the head. If it ia a front seal you would have oil on the inside top of the motor cowling from the turning of the belts and pulleys. |
Posted By: The Dude
Date Posted: March-07-2005 at 12:33am
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I just replaced engine in my 87 Supra and the first symptom was oil pooled on top of manifold. It came from the blow by hoses...
79 and David F are wizards. ------------- Mullet Free since 93 http://www.correctcraftfan.com/diaries/details.asp?ID=717&sort=&pagenum=1&yrstart=1991&yrend=1995 - 95 Sport |
Posted By: captan1
Date Posted: March-08-2005 at 1:19pm
I think it's a cosmic falatium on the upper statiscope.  ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=452&sort=&pagenum=1&yrstart=1978&yrend=1978 - 1978 Ski Nautique |