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Oil fouling number 3 spark plug

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Crownvicjohn Avatar
Crownvicjohn Silver Member John P
Wolcott, Connecticut, USA   USA
1980 MG MGB Limited Edition (LE) "The Convertible"
1995 Buick Roadmaster "The Woody"
2011 Ford Crown Victoria "The Vic"
I swapped a short block into my 1980 B and re-used the rebuilt head I had on my old engine.
Now I am fouling number 3 spark plug with oil and oil is on the spark plug treads and the sealing ring and it looks wet with oil around the spark plug well. ( Not coolant )
Compression is good, 162 to 167 across the board and oil pressure is great.
I am leaning toward a crack in the head around the spark plug but it wasn't doing this on the old engine. Maybe by removing and re- installing It cracked?
I have another head I can swap out to see if it's that.


A ten year old post by Basil Adams gave me this idea.

http://www.mgexp.com/phorum/read.php?1,497131

Otherwise the engine is running great, compared to my old tired one.

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dipstick Avatar
dipstick Kenny Snyder
La Center, Washington, USA   USA
1941 Ford N-Series
1958 MG MGA 1500 Coupe "Rosie"
1970 MG MGB GT "Pat's GT"
1971 MG MGB "Gifted To Me"    & more
Please supply the casting number of the head with the oil on #3 spark plug. The casting number is underneath the valve cover on top of the head. Some casting numbers are more prone to cracking than others. All that said, a cracked head generally looses coolant, not oil. With the valve cover off clean the cylinder head valve cover gasket surface above #3 and look for a crack leading toward #3 exhaust valve.



Be safe out there.
Kenny

RAY 67 TOURER Avatar
RAY 67 TOURER Ray Marloff
Fort Bragg, CA, USA   USA
1967 MG MGB "My Girl"
Sounds like a stuck oil control ring on #3 piston ring. However, it won't have any effect on your compression readings. RAY

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dickmoritz Avatar
dickmoritz Gold Member Dick Moritz
Philly 'burbs, PA, USA   USA
What Ray said...

Dick

In reply to # 3562153 by RAY 67 TOURER Sounds like a stuck oil control ring on #3 piston ring. However, it won't have any effect on your compression readings. RAY



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

nickj Avatar
nickj Gold Member Nick Jenkins
Novato, Marin Co, CA, USA   USA
1970 MG MGB GT
1972 MG MGB
I would definitely want to pull the head and at least look at the #3 cylinder wall. Hopefully it's just the oil ring. Before I replaced the rings on my '72 I was burning a quart of oil every 50 miles, but it didn't leave oil on the spark plugs, it just burned and went out the exhaust. Oil on the plug sounds like something my MGA did when a rod got slightly bent and scuffed the piston.

Crownvicjohn Avatar
Crownvicjohn Silver Member John P
Wolcott, Connecticut, USA   USA
1980 MG MGB Limited Edition (LE) "The Convertible"
1995 Buick Roadmaster "The Woody"
2011 Ford Crown Victoria "The Vic"
In reply to # 3562152 by dipstick Please supply the casting number of the head with the oil on #3 spark plug. The casting number is underneath the valve cover on top of the head. Some casting numbers are more prone to cracking than others. All that said, a cracked head generally looses coolant, not oil. With the valve cover off clean the cylinder head valve cover gasket surface above #3 and look for a crack leading toward #3 exhaust valve.

The casting number on the head is CAM1106 AF1H. I don't see any cracks. I guess the first step is to pull the head and look around cylinder 3. If I don't see any problem with the head I will pull the engine and remove the piston and look at the rings. While it's out I will replace the rear main seal which leaks. Sound like a plan?

Is it even possible for a crack in the head to leak oil around the spark plug? Maybe I misunderstood Basil's post.

http://www.mgexp.com/phorum/read.php?1,497131 ( Post 12)

dickmoritz Avatar
dickmoritz Gold Member Dick Moritz
Philly 'burbs, PA, USA   USA
CAM1106 head is notorious for cracking, particularly in the vicinity of cylinder number 3. If you're going to pull the head for any reason, be certain to get it magnafluxed and/or pressure tested...

Dick

In reply to # 3563010 by Crownvicjohn
In reply to # 3562152 by dipstick Please supply the casting number of the head with the oil on #3 spark plug. The casting number is underneath the valve cover on top of the head. Some casting numbers are more prone to cracking than others. All that said, a cracked head generally looses coolant, not oil. With the valve cover off clean the cylinder head valve cover gasket surface above #3 and look for a crack leading toward #3 exhaust valve.

The casting number on the head is CAM1106 AF1H. I don't see any cracks. I guess the first step is to pull the head and look around cylinder 3. If I don't see any problem with the head I will pull the engine and remove the piston and look at the rings. While it's out I will replace the rear main seal which leaks. Sound like a plan?

Is it even possible for a crack in the head to leak oil around the spark plug? Maybe I misunderstood Basil's post.

http://www.mgexp.com/phorum/read.php?1,497131 ( Post 12)



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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Crownvicjohn Avatar
Crownvicjohn Silver Member John P
Wolcott, Connecticut, USA   USA
1980 MG MGB Limited Edition (LE) "The Convertible"
1995 Buick Roadmaster "The Woody"
2011 Ford Crown Victoria "The Vic"
In reply to # 3563035 by dickmoritz CAM1106 head is notorious for cracking, particularly in the vicinity of cylinder number 3. If you're going to pull the head for any reason, be certain to get it magnafluxed and/or pressure tested...

Dick

In reply to # 3563010 by Crownvicjohn

So have you ever heard of a cracked head leaking oil in this area or only coolant? There is no coolant leak. Thanks.

dickmoritz Avatar
dickmoritz Gold Member Dick Moritz
Philly 'burbs, PA, USA   USA
Yup...

Dick

In reply to # 3563048 by Crownvicjohn
In reply to # 3563035 by dickmoritz CAM1106 head is notorious for cracking, particularly in the vicinity of cylinder number 3. If you're going to pull the head for any reason, be certain to get it magnafluxed and/or pressure tested...

Dick

In reply to # 3563010 by Crownvicjohn

So have you ever heard of a cracked head leaking oil in this area or only coolant? There is no coolant leak. Thanks.



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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Crownvicjohn Avatar
Crownvicjohn Silver Member John P
Wolcott, Connecticut, USA   USA
1980 MG MGB Limited Edition (LE) "The Convertible"
1995 Buick Roadmaster "The Woody"
2011 Ford Crown Victoria "The Vic"
Update: I removed the head and couldn't see any cracks. I had a new County head I bought for another engine last year when they were on sale at Moss. I ported and polished it because it was pretty rough and I installed it on this engine. After 140 miles today I pulled the plugs and they looked good. I'll check again in another 500 miles. Strange how that old head was good on one engine and bad on another, unless just removing and installing it cracked it. I will remove the valves and check further. Thanks guys.

Crownvicjohn Avatar
Crownvicjohn Silver Member John P
Wolcott, Connecticut, USA   USA
1980 MG MGB Limited Edition (LE) "The Convertible"
1995 Buick Roadmaster "The Woody"
2011 Ford Crown Victoria "The Vic"
After 500 miles there is no fouling of the spark plug number 3. I looked at the tops of the pistons through the spark plug holes and number 3 is black and the other three are dark tan. Maybe this will clear up in time.
I can see a possible crack above the intake valve on the old head but I'm not sure.
My compression dropped a little going from the CAM1106 head to the County smog head. They were 162-167psi. Now they are 155-162.
I'm going to run the car for another month because there are a couple of British shows around here I want to take it to.
Then I will pull the engine to replace the rear main seal but if all remains as is I won't have to pull the piston to look for a ring problem.
Good, one less thing. Thanks guys.

Crownvicjohn Avatar
Crownvicjohn Silver Member John P
Wolcott, Connecticut, USA   USA
1980 MG MGB Limited Edition (LE) "The Convertible"
1995 Buick Roadmaster "The Woody"
2011 Ford Crown Victoria "The Vic"
It's been about 1100 miles now and it's still good. I guess it was the head. Strange how it was good on one engine and bad on another. I'm going to have it magnafluxed to see if it's scrap. I pulled the engine this week to fix the oil leak. The rear main seal leaked a little but the main leak was from the back plate gasket. It did need a speedisleeve too. Thanks for all the help.

Donthuis Avatar
Donthuis Don van Riet
Rijswijk, ZH, Netherlands   NLD
Well RAY I have the same on cyl #2, but fine, very even (+/- 5%) compression values across all cylinders. So I wondered and your answer seems what I am looking for eye rolling smiley
Strangely enough I used a ring freeing agent as one part of an additive aimed to older engines, later I put a compression and oil pressure raising one in, it looks like the STP I knew from years ago.

In reply to # 3562153 by RAY 67 TOURER Sounds like a stuck oil control ring on #3 piston ring. However, it won't have any effect on your compression readings. RAY

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