Mastiff 2008 EFI Head Gasket leak.

[Bolly]

Hi Fellow Dog Owners..
Its been leaking oil for a while but very slightly..
Ive been wiping the oil off after every ride..
Its the back Cylinder Head that leaking oil at the rear, near the head bolt..
I bought the bike with 1,800ks and its always had a oil burning smell.
Its now at 4,000ks and decided to do something about it, so ive bought a head gasket kit .......
Thought id ask some questions though..
Was this a common problem especially with very low ks?
The rocker cover was also leaking but that was a easy fix..

Being a Mastiff, im hoping that i dont have to remove the engine to remove the head..
Ive just looked at the PDF Service Manual and the 117 SS motor has stretch head bolts..
Thats another month ill have to wait for New bolts ..
Is there a supplier that offers Non stretch bolts?

Cheers............. Kevin from Adelaide Australia..

 

[pknowles]

Are you sure it's the head gasket.

 

[Mikeinjersey]

Hi Fellow Dog Owners..
Its been leaking oil for a while but very slightly..
Ive been wiping the oil off after every ride..
Its the back Cylinder Head that leaking oil at the rear, near the head bolt..
I bought the bike with 1,800ks and its always had a oil burning smell.
Its now at 4,000ks and decided to do something about it, so ive bought a head gasket kit .......
Thought id ask some questions though..
Was this a common problem especially with very low ks?
The rocker cover was also leaking but that was a easy fix..

Being a Mastiff, im hoping that i dont have to remove the engine to remove the head..
Ive just looked at the PDF Service Manual and the 117 SS motor has stretch head bolts..
Thats another month ill have to wait for New bolts ..
Is there a supplier that offers Non stretch bolts?

Cheers............. Kevin from Adelaide Australia..View attachment 96329

I think it's more likely you only have a rocker box gasket leak. If it was your head gasket you would have performance issues from loss of compression. If I'm right, no need to loosen the head bolts so you won't need new one's. Some mechanics I've spoken to don't replace then anyway. I'm not sure if that is a good policy.
One theory on causes of oil leaks is not letting the engine be fully warmed up before getting on the throttle heavy. I ride for at lease 15min before hard acceleration.
Great license plate!!

 

[Jwooky]

Likely the rocker box gasket, especially being the rear, they get a lot hotter.

did mine a few years back, super tight but can be done in bike.

had to cut down an Allen wrench.

 

[Bolly]

Are you sure it's the head gasket.

Clearly Positive.!

 

[Bolly]

I think it's more likely you only have a rocker box gasket leak. If it was your head gasket you would have performance issues from loss of compression. If I'm right, no need to loosen the head bolts so you won't need new one's. Some mechanics I've spoken to don't replace then anyway. I'm not sure if that is a good policy.
One theory on causes of oil leaks is not letting the engine be fully warmed up before getting on the throttle heavy. I ride for at lease 15min before hard acceleration.
Great license plate!!

The rocker box was leaking but that was sorted out..
The head gasket is clearly leaking..
Thanks about the licence plate

 

[Mikeinjersey]

The rocker box was leaking but that was sorted out..
The head gasket is clearly leaking..
Thanks about the licence plate

Verify with a compression test or leak down test before you pull the head. Can you take a pic of the leak? Any chance we are using different terms for the gaskets? As in possibly cylinder base gasket. They like to leak and you would obviously need to pull the head to replace it.

 

[Mickmorris]

Is it showing oil on the engine fin nearest to the bottom bolt on the exhaust manifold on the rear cylinder?

 

[john sachs]

If you are sure it's a head gasket that's causing the leak, and you mentioned something about stretched studs, I will tell you that I've NEVER seen a H.D, or S&S stud stretch. You may find, if 1 stud is taller (sticking up higher) than the others, that the stud is trying to pull out of the case. It's not uncommon. I find this every once in a while. If so, it needs to be fixed with an oversized insert to hold the stud, meaning the cylinder has to be removed as well.
Another area to check would be the inside of the exhaust port on the cylinder in question. If a guide, or seal is bad, it will leak oil from the exhaust port, and port area.
Last resort, clean everything, and spray some foot powder in the area, ride a mile or so, and you should be able to see exactly where the leaks are coming from.
John

 

[Bolly]

Verify with a compression test or leak down test before you pull the head. Can you take a pic of the leak? Any chance we are using different terms for the gaskets? As in possibly cylinder base gasket. They like to leak and you would obviously need to pull the head to replace it.

It's clearly the head gasket ,I've been wiping it after every ride for 2 years..Cheers..

 

[Bolly]

Is it showing oil on the engine fin nearest to the bottom bolt on the exhaust manifold on the rear cylinder?

It's leaking as you said But on the spark plug side engine Fin on the rear cylinder..

 

[bdm7250]

Hi Fellow Dog Owners..
Its been leaking oil for a while but very slightly..
Ive been wiping the oil off after every ride..
Its the back Cylinder Head that leaking oil at the rear, near the head bolt..
I bought the bike with 1,800ks and its always had a oil burning smell.
Its now at 4,000ks and decided to do something about it, so ive bought a head gasket kit .......
Thought id ask some questions though..
Was this a common problem especially with very low ks?
The rocker cover was also leaking but that was a easy fix..

Being a Mastiff, im hoping that i dont have to remove the engine to remove the head..
Ive just looked at the PDF Service Manual and the 117 SS motor has stretch head bolts..
Thats another month ill have to wait for New bolts ..
Is there a supplier that offers Non stretch bolts?

Cheers............. Kevin from Adelaide Australia..View attachment 96329

Kevin, You asked if it was common. If the previous owner had a habit of firing up the bike and tearing off right away it is far more common than waiting for the motor to get up to operating temperature before putting load on it. Evo engines don't like being beat on when they're cold.

 

[Mickmorris]

It's leaking as you said But on the spark plug side engine Fin on the rear cylinder..

So yeah clearly a head gasket. Good luck! Let us know how you make out. I am not sure about the removing the engine part but I think it might be easier to do it that way. Keep us in the loop on your progress!

 

[Bolly]

Kevin, You asked if it was common. If the previous owner had a habit of firing up the bike and tearing off right away it is far more common than waiting for the motor to get up to operating temperature before putting load on it. Evo engines don't like being beat on when they're cold.

I've always warmed up the bike but it was already leaking when I bought it..

 

[bdm7250]

I've always warmed up the bike but it was already leaking when I bought it..

That's why I blamed the previous owner in my post..