Go Back  Offshoreonly.com > Technical > General Q & A
Oil out the exhaust >

Oil out the exhaust

Notices

Oil out the exhaust

Thread Tools
 
Old 06-04-2019 | 07:00 AM
  #1  
Thread Starter
Registered
 
Joined: Jul 2017
Posts: 8
Likes: 0
Default Oil out the exhaust

Ok, 496 BBC, I have oil blowing by and out the exhaust. On a hard run, about 2hrs I run through 4q of oil. It's not burning it, its raw dump out the exhaust. I have zero power loss, and the compression on each cylinder is above 150. Any ideas?
zeek987 is offline  
Reply
Old 06-04-2019 | 07:20 AM
  #2  
Registered
10 Year Member
 
Joined: Oct 2012
Posts: 2,230
Likes: 536
Default

Oil cooler
underpsi68 is offline  
Reply
Old 06-04-2019 | 07:25 AM
  #3  
Thread Starter
Registered
 
Joined: Jul 2017
Posts: 8
Likes: 0
Default

I should mention that I do have signs of build up on my plugs.
zeek987 is offline  
Reply
Old 06-04-2019 | 08:54 AM
  #4  
Registered
 
Joined: Apr 2013
Posts: 203
Likes: 0
From: Lake Winnebago
Default

Wrong dipstick?....causing you to overfill the pan....oil coming out breather into the intake....being blown out?

Since:
1. "no power loss"
2. oil build up on plugs
3. Good compression

It be looking for a leak down tester too.....

Is this a fresh build? how many hours? Details.

I like the oil cooler idea...but then you shouldnt have build up on the plugs.

Last edited by SS496; 06-04-2019 at 08:58 AM.
SS496 is offline  
Reply
Old 06-04-2019 | 08:54 AM
  #5  
Registered
 
Joined: Mar 2012
Posts: 4,189
Likes: 55
From: Cape coral, FL
Default

Oil cooler
Crude Intentions is offline  
Reply
Old 06-04-2019 | 08:58 AM
  #6  
Knot 4 Me's Avatar
Registered
20 Year Member
 
Joined: Jun 2005
Posts: 8,407
Likes: 797
From: Central IL
Default

Are you running guide seals on exhaust valves? Excessive guide clearance?
Knot 4 Me is offline  
Reply
Old 06-04-2019 | 09:04 AM
  #7  
Registered
15 Year Member
 
Joined: Oct 2007
Posts: 8,439
Likes: 93
From: yorkville,il
Default

pressure test the oil cooler.
mike tkach is offline  
Reply
Old 06-04-2019 | 09:10 AM
  #8  
BUP
Banned
 
Joined: Jul 2011
Posts: 9,594
Likes: 45
From: Ft. Worth TX
Default

Pressure test the oil cooler first very easy to do --- if that checks out good on the pressure testing - next place I would check would be --- possible intake manifold gasket - a engine serial number is a must.

Later 496 changed to a bigger intake manifold gasket for better sealing because the first gen was not holding up over time. As you mentioned plugs have build up but is that OIL OR GAS.
BUP is offline  
Reply
Old 06-04-2019 | 09:14 AM
  #9  
Registered
 
Joined: Mar 2012
Posts: 4,189
Likes: 55
From: Cape coral, FL
Default

4qts in 2 hours is a lot for blow by. I would be pulling and testing oil cooler ASAP. I mean that’s half the pan oil coming out. Mine did something similar and it was cooler.
Crude Intentions is offline  
Reply
Old 06-04-2019 | 10:23 AM
  #10  
Thread Starter
Registered
 
Joined: Jul 2017
Posts: 8
Likes: 0
Default

The motor is a built carb, 496, not a mercruiser, I run a larger oil pan so the boat actually takes about 10+ quarts. I have a guy that is going to do a leak down test for me but I have to wait 2-3 weeks. The oil cooler is a good idea, I never thought of that. It is not a stock one either of course, it is a much larger one. But that does not mean something didnt happen to it.
zeek987 is offline  
Reply


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.