Home » Public Forums » GMCnet » [GMCnet] High oil consumption maybe solved
[GMCnet] High oil consumption maybe solved [message #250066] |
Sun, 18 May 2014 18:19 |
glwgmc
Messages: 1014 Registered: June 2004
Karma: 10
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Senior Member |
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A while back I posted about the seemingly high oil use in the Clasco, about a quart every 200 to 300 miles. I checked all the normal suspects (dip stick calibration, PCV system, leaky pan gasket, leaky valve cover gaskets, oil cooler lines and fittings, etc.) and also found the plugs were all a nice chocolate brown so that tended to rule out internal things like valve guides or worn rings, etc. Finally, I added a bottle of dye to the oil and drove it until a quart had gone somewhere and took it to a mechanic with an oil change pit. Using a black light and the special goggles he could see oil coming down the front of the engine from the area where the intake manifold gasket runs across the "china wall" (the thin casting at the front of the valley between the two cylinder banks). This is a 77 coach and originally had the rubber surround around the radiator fan. That configuration required a couple of large brackets bolted to the front side of the engine to support it. I r
emoved that mess last year and put in one of the split type fan shrouds that make it much easier to change out the fan clutch, but I left two of those vestigial brackets in place as they were a bit hard to get to and I was lazy at the time. With those brackets in place it was hard to see the front of the engine clearly so I removed them and could see the culprit. A large piece of the rubber gasket that was supposed to seal the china wall to the intake manifold had pouched out leaving a significant gap where oil fumes from the valley area or even liquid oil in that region could find their way out. The fan would pick up the oil and move it back across the hot manifolds where it evaporated as we drove. Hence, we did not see heavy leakage onto the ground and did not see blue smoke from the tail pipe, but a lot of oil came out of that gap.
Today I had the mechanic come over and remove the intake manifold (too heavy and awkward for these old bones). Close examination failed to show any cracking at all either along the bottom of the cross over area (the cross over had never been blocked) or along the wall between the secondary bores. So, it was heavy cleaning time on the manifold. The original turkey tray was caked both sides with burned oil residue but the valley was quite clean. From inspection of the turkey tray area around a couple of the intake ports it looks like there may have been some leakage there as well but it did not show up on those plugs. We carefully cleaned the heads, vacuumed out the valley floor and the ports in the intake manifold and put it all back together with Great Stuff RTV and the block off plate gasket set from Jim K. We did not use the rubber pieces along the china wall but instead used a good bead of the Great Stuff. Everything appeared to seal correctly and hopefully that wil
l be the end of the high oil use. We are headed for the Cascader ralley at Pheasant Ridge RV Resort in Wilsonville, just south of Portland, this next week (about a 600 mile round trip). All the gang that will be doing the Route 66 Rally will be there as their official kickoff. Should be fun. I will keep you posted as to whether replacing the intake manifold gasket solves the issue or not. Hope so.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
Visitors always welcome!
glwork@mac.com
http://jerrywork.com
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Jerry & Sharon Work
78 Royale
Kerby, OR
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Re: [GMCnet] High oil consumption maybe solved [message #250069 is a reply to message #250066] |
Sun, 18 May 2014 18:38 |
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USAussie
Messages: 15912 Registered: July 2007 Location: Sydney, Australia
Karma: 6
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Senior Member |
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Jerry,
Just a couple of points regarding R&R of the intake manifold:
1) I assume you got Dick Paterson's crossover manifold gasket kit from JimK, I mention that because Dick uses gasket material that
is 0.027 thick which when torqued results in a gasket that is the same thickness as the turkey tray. IIRC the rest of the
aftermarket gaskets are 0.060 thick and that can cause problems with port alignment. For those of you that want to make your own
intake manifold gaskets you can buy 0.027 thick gasket material from the major auto parts stores in the USA.
2) It is important to use Oxygen sensor compatible RTV on the intake manifold. Even if you don't run EFI the next person that owns
your coach might decide to install it and they'll appreciate you doing so! Dick recommends NOT to use red hi-temp RTV with his
gasket kit.
Regards,
Rob M.
-----Original Message-----
From: Work Jerry
A while back I posted about the seemingly high oil use in the Clasco, about a quart every 200 to 300 miles. I checked all the
normal suspects (dip stick calibration, PCV system, leaky pan gasket, leaky valve cover gaskets, oil cooler lines and fittings,
etc.) and also found the plugs were all a nice chocolate brown so that tended to rule out internal things like valve guides or worn
rings, etc. Finally, I added a bottle of dye to the oil and drove it until a quart had gone somewhere and took it to a mechanic
with an oil change pit. Using a black light and the special goggles he could see oil coming down the front of the engine from the
area where the intake manifold gasket runs across the "china wall" (the thin casting at the front of the valley between the two
cylinder banks). This is a 77 coach and originally had the rubber surround around the radiator fan. That configuration required a
couple of large brackets bolted to the front side of the engine to support it. I r
emoved that mess last year and put in one of the split type fan shrouds that make it much easier to change out the fan clutch, but
I left two of those vestigial brackets in place as they were a bit hard to get to and I was lazy at the time. With those brackets
in place it was hard to see the front of the engine clearly so I removed them and could see the culprit. A large piece of the
rubber gasket that was supposed to seal the china wall to the intake manifold had pouched out leaving a significant gap where oil
fumes from the valley area or even liquid oil in that region could find their way out. The fan would pick up the oil and move it
back across the hot manifolds where it evaporated as we drove. Hence, we did not see heavy leakage onto the ground and did not see
blue smoke from the tail pipe, but a lot of oil came out of that gap.
Today I had the mechanic come over and remove the intake manifold (too heavy and awkward for these old bones). Close examination
failed to show any cracking at all either along the bottom of the cross over area (the cross over had never been blocked) or along
the wall between the secondary bores. So, it was heavy cleaning time on the manifold. The original turkey tray was caked both
sides with burned oil residue but the valley was quite clean. From inspection of the turkey tray area around a couple of the intake
ports it looks like there may have been some leakage there as well but it did not show up on those plugs. We carefully cleaned the
heads, vacuumed out the valley floor and the ports in the intake manifold and put it all back together with Great Stuff RTV and the
block off plate gasket set from Jim K. We did not use the rubber pieces along the china wall but instead used a good bead of the
Great Stuff. Everything appeared to seal correctly and hopefully that wil
l be the end of the high oil use. We are headed for the Cascader ralley at Pheasant Ridge RV Resort in Wilsonville, just south of
Portland, this next week (about a 600 mile round trip). All the gang that will be doing the Route 66 Rally will be there as their
official kickoff. Should be fun. I will keep you posted as to whether replacing the intake manifold gasket solves the issue or
not. Hope so.
Jerry
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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Re: [GMCnet] High oil consumption maybe solved [message #250091 is a reply to message #250066] |
Sun, 18 May 2014 22:08 |
Bob de Kruyff
Messages: 4260 Registered: January 2004 Location: Chandler, AZ
Karma: 1
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Senior Member |
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glwgmc wrote on Sun, 18 May 2014 17:19A while back I posted about the seemingly high oil use in the Clasco, about a quart every 200 to 300 miles. I checked all the normal suspects (dip stick calibration, PCV system, leaky pan gasket, leaky valve cover gaskets, oil cooler lines and fittings, etc.) and also found the plugs were all a nice chocolate brown so that tended to rule out internal things like valve guides or worn rings, etc. Finally, I added a bottle of dye to the oil and drove it until a quart had gone somewhere and took it to a mechanic with an oil change pit. Using a black light and the special goggles he could see oil coming down the front of the engine from the area where the intake manifold gasket runs across the "china wall" (the thin casting at the front of the valley between the two cylinder banks). This is a 77 coach and originally had the rubber surround around the radiator fan. That configuration required a couple of large brackets bolted to the front side of the engine to support it. I r
emoved that mess last year and put in one of the split type fan shrouds that make it much easier to change out the fan clutch, but I left two of those vestigial brackets in place as they were a bit hard to get to and I was lazy at the time. With those brackets in place it was hard to see the front of the engine clearly so I removed them and could see the culprit. A large piece of the rubber gasket that was supposed to seal the china wall to the intake manifold had pouched out leaving a significant gap where oil fumes from the valley area or even liquid oil in that region could find their way out. The fan would pick up the oil and move it back across the hot manifolds where it evaporated as we drove. Hence, we did not see heavy leakage onto the ground and did not see blue smoke from the tail pipe, but a lot of oil came out of that gap.
Today I had the mechanic come over and remove the intake manifold (too heavy and awkward for these old bones). Close examination failed to show any cracking at all either along the bottom of the cross over area (the cross over had never been blocked) or along the wall between the secondary bores. So, it was heavy cleaning time on the manifold. The original turkey tray was caked both sides with burned oil residue but the valley was quite clean. From inspection of the turkey tray area around a couple of the intake ports it looks like there may have been some leakage there as well but it did not show up on those plugs. We carefully cleaned the heads, vacuumed out the valley floor and the ports in the intake manifold and put it all back together with Great Stuff RTV and the block off plate gasket set from Jim K. We did not use the rubber pieces along the china wall but instead used a good bead of the Great Stuff. Everything appeared to seal correctly and hopefully that wil
l be the end of the high oil use. We are headed for the Cascader ralley at Pheasant Ridge RV Resort in Wilsonville, just south of Portland, this next week (about a 600 mile round trip). All the gang that will be doing the Route 66 Rally will be there as their official kickoff. Should be fun. I will keep you posted as to whether replacing the intake manifold gasket solves the issue or not. Hope so.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
Visitors always welcome!
glwork@mac.com
http://jerrywork.com
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Jerry I hope you are on to something, but experience makes me think you have some serious engine problems such as valve guides or piston ring issues.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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Re: [GMCnet] High oil consumption maybe solved [message #255326 is a reply to message #250066] |
Mon, 14 July 2014 11:55 |
fred v
Messages: 999 Registered: April 2006 Location: pensacola, fl.
Karma: 0
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Senior Member |
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I've had this same problem since buying my coach in '06. This morning I looked and found the front of the engine quite wet with oil as well as the rear. I had removed the manifold in '07 and used the block off gaskets and blue RTV to seal the wall. Looks like it didn't seal.
I had gone through all the fixes, even replaced the inlet valve seals with positive seals. I think my engine is a Toronado as it didn't have the motorhome valve covers. Changing those did nothing. At that point I stopped throwing money at the problem but this looks promising.
Fred V
'77 Royale RB 455
P'cola, Fl
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Re: [GMCnet] High oil consumption maybe solved [message #255332 is a reply to message #250066] |
Mon, 14 July 2014 12:39 |
Steve
Messages: 506 Registered: September 2013 Location: East Greenville, Pa
Karma: 1
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Senior Member |
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When sealing the front and rear of the intake manifold with RTV Black, I am always careful to set the manifold and then let the RTV set up before tightening and torquing the manifold down. Best to carefully follow the directions of the product you are using. I have had better results when I follow this procedure. I also re-torque the manifold bolts a couple of times after driving for a couple hundred miles.
JWID
1978 GMC Royal
Eastern Pennslyvania
1968 Chevrolet C20 396 Camper Special
1969 Chevrolet C20 Camper Special
1985 Buick Electra Park Avenue
1992 Camaro 25th Anniversary Heretage Edition Black
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Re: [GMCnet] High oil consumption maybe solved [message #255336 is a reply to message #255326] |
Mon, 14 July 2014 13:21 |
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WD0AFQ
Messages: 7111 Registered: November 2004 Location: Dexter, Mo.
Karma: 207
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fred v wrote on Mon, 14 July 2014 11:55I've had this same problem since buying my coach in '06. This morning I looked and found the front of the engine quite wet with oil as well as the rear. I had removed the manifold in '07 and used the block off gaskets and blue RTV to seal the wall. Looks like it didn't seal.
I had gone through all the fixes, even replaced the inlet valve seals with positive seals. I think my engine is a Toronado as it didn't have the motorhome valve covers. Changing those did nothing. At that point I stopped throwing money at the problem but this looks promising.
Fred, you might seal it without removing intake, I did. But, I could see the exact places, front and back, where it leaked. I had three or four big gaps where the tv had come out. I used a mirror in front, cleaned it up good with brake fluid. Then I shoved new rtv into the holes and let set for a week. Started it up, and never another leak. Been over a year now. Mine was pouring oil out, no doubt I had a serious problem.
Dan
Enjoying our roof air today
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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Re: [GMCnet] High oil consumption maybe solved [message #255340 is a reply to message #255336] |
Mon, 14 July 2014 13:45 |
midlf
Messages: 2212 Registered: July 2007 Location: SE Wisc. (Palmyra)
Karma: 1
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WD0AFQ wrote on Mon, 14 July 2014 13:21
Fred, you might seal it without removing intake, I did. But, I could see the exact places, front and back, where it leaked. I had three or four big gaps where the tv had come out. I used a mirror in front, cleaned it up good with brake fluid. Then I shoved new rtv into the holes and let set for a week. Started it up, and never another leak. Been over a year now. Mine was pouring oil out, no doubt I had a serious problem.
Dan
Enjoying our roof air today
Dan did you mean brake cleaning fluid instead of brake fluid?
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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Re: [GMCnet] High oil consumption maybe solved [message #255599 is a reply to message #255340] |
Wed, 16 July 2014 13:15 |
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WD0AFQ
Messages: 7111 Registered: November 2004 Location: Dexter, Mo.
Karma: 207
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midlf wrote on Mon, 14 July 2014 13:45WD0AFQ wrote on Mon, 14 July 2014 13:21
Fred, you might seal it without removing intake, I did. But, I could see the exact places, front and back, where it leaked. I had three or four big gaps where the tv had come out. I used a mirror in front, cleaned it up good with brake fluid. Then I shoved new rtv into the holes and let set for a week. Started it up, and never another leak. Been over a year now. Mine was pouring oil out, no doubt I had a serious problem.
Dan
Enjoying our roof air today
Dan did you mean brake cleaning fluid instead of brake fluid?
Yes, I did. Cleaning fluid I sprayed and cleaned. It was not hard but the mirror is a must to see the front of intake.
Should you not see where it is leaking, clean everything up good then run engine. Use the mirror and see if you can spot it. I had a similar problem with my edelbroch on my 289 in the mustang. It was easy so I just pulled and cleaned then re sealed. Never to leak again, so far, either of them.
I bet you can find it Fred. The mirror is a telescoping one that can be bought at any parts house or harbor freight. Clean is very important so the rtv sticks.
Mine may have sucked the rtv inside the engine, since there were chunks missing. So, I ran engine then changed the oil.
Dan
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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