Some info requested - blown valve cover gasket, oil pressure sensor, or both?

[ohiorider]

I was preparing to clean up the 1200 Sport for the upcoming riding season, when I noticed lots of black sooty crap on the cylinder fins and below them.  Thinking I'd blown a valve cover gasket, I set out to replace it, but decided to pull the tank and take a closer look.

Yes, it looks like the valve cover gasket could have given up, but up a bit deeper in the works there appears to be another leak.  Hopefully one of you will recognize it.  Without pulling an engine parts drawing, I'm thinking it is the oil pressure sensor.  If that's the case, it appears the air box should come off to get to it.

While I'm in there replacing the oil pressure sensor (assuming that's what is leaking), any other items of interest I should be checking?  I'm certain I can get one either locally or from one of our mail order folks.  I thought I recalled there being an automotive part that was identical to the sensor used on the big block Guzzis.


Left Cylinder from front - any chance there could also be a blown exhaust gasket?








Looking up at bottom of left cylinder and at possible offending part

[Vasco DG]

That part is the phase sensor and yes, they are leak prone. Be aware that when you remove it it may have one or more shims between it and the case. Don't loose them when you remove the sensor. Seal it with a thin smear of Threebond on the mating surfaces and both sides of the shim. I have to do it on my old girl too.

Pete

[ohiorider]

Pete, is the leak caused by failing gaskets, or does the phase sensor itself 'spring a leak?'

Thanks for the quick response, BTW!

Bob

[Vasco DG]

From memory the sensor has an o-ring that sits in a taper in the case under the shim. It's a rotten way of sealing it. Hence the threebond. No, the sensor itself doesn't leak.

Pete

[Bisbonian]

Mine had a leak at that sensor last year Bob.

There were a number of thin metal shims to keep track of.

I used a bit of Yamabond like Pete suggests and no leak since.

[ohiorider]

Thanks, all!  Biz, if anyone has been thru some  issues and stayed the course, it is you and your red and white Sport.  With 54,500 miles (nearly) showing on the odometer of my b&w Sport, I've got absolutely no complaints with my favorite Guzzi.  I've got the tank off, so it shouldn't take too much effort to get to the offending part.  In the meantime, the 2012 Griso 8vSE is running better and better, so I should have a Guzzi to ride while I get to the source of the leak.

Bob

[Wayne Orwig]

I have found a number of things with the phase sensor leak.
A. As mentioned, pay attention to the shims.
B. I have had the plastic develop small cracks. The heat hardens the o-ring that is on it, and also distorts and cracks the plastic a bit.
C. I clean them very thoroughly to get any oil out of the cracks in the plastic. Then do as Pete states with the sealant.
D. I've never had any luck using just sealant. If I touch it, I put a new o-ring on it.
E. When I bought new o-rings for some bikes a few months back, they had a new number. I'm not sure, but I wonder if they switched to a higher temperature o-ring.

Edit: I just looked it up. The old number was 90706141. The new part number is 847180. No idea why it changed.

[ohiorider]

Thanks for the new o ring part #, Wayne.  Ordering them today.  I'm thinking the plastic part(s) you reference in your post are the shim(s)?  I found the old PN in the 1200 Sport parts manual, and it appeared there were several different shims .... different thicknesses, looks like.

20 Phase/revolution sensor - - - - - GU01721600 1 AN049
21 O-ring - - - - - GU90706141 1 -
22 Gasket 1,5mm - - - - - GU01722705 1 AO349
Gasket 0,5 mm - - - - - GU29722760 1 AO349
Gasket 1mm - - - - - GU01722704 1 AO349
Gasket 0,8mm - - - - - GU01722703 1 AO349
Gasket 0,6mm - - - - - GU01722702 1 AO349
Gasket 0,4mm - - - - - GU01722701 1 AO349
Gasket 0,3mm -

Bob

[Wayne Orwig]

Thanks for the new o ring part #, Wayne.  Ordering them today.  I'm thinking the plastic part(s) you reference in your post are the shim(s)?  I found the old PN in the 1200 Sport parts manual, and it appeared there were several different shims .... different thicknesses, looks like.

20 Phase/revolution sensor - - - - - GU01721600 1 AN049
21 O-ring - - - - - GU90706141 1 -
22 Gasket 1,5mm - - - - - GU01722705 1 AO349
Gasket 0,5 mm - - - - - GU29722760 1 AO349
Gasket 1mm - - - - - GU01722704 1 AO349
Gasket 0,8mm - - - - - GU01722703 1 AO349
Gasket 0,6mm - - - - - GU01722702 1 AO349
Gasket 0,4mm - - - - - GU01722701 1 AO349
Gasket 0,3mm -

Yes, they come in different thicknesses, they are shims.  ~;

They are thin aluminium. You do not need to replace them, only the o-ring, plus add some sealant.
The plastic I referred to is the sensor itself. Clean it. Reinstall the original aluminium shims. Install a new o-ring. Wipe some sealant on the plastic sensor body. Shove back in hole. Bolt down. Go ride.

 

[twodogs]

I had Jim at rose farm replace the o ring on mine, took care of that leak, I was thinking it was the oil sensor and got one for him to change out, turns out I got the wrong one and he did not have one in stock so we left it alone, this week it went belly up so he is sending me one plus the exhaust gasket and I'll change it out myself, looks like fun. :BEER: When my valve cover gasket went out on that side it was blowing the oil right onto the header, looked like yours in the pic. Ride safe.

[Vasco DG]

Bob, if it does turn out to be the valve cover gasket try and get hold of a pair of the Valpolini gaskets. I dunno if they are being bought into the US yet or not? If you can't find 'em gimme a hoy and I'll send you a pair they are the definitive answer to leaky gaskets on late model bikes.

Pete

[ohiorider]

Bob, if it does turn out to be the valve cover gasket try and get hold of a pair of the Valpolini gaskets. I dunno if they are being bought into the US yet or not? If you can't find 'em gimme a hoy and I'll send you a pair they are the definitive answer to leaky gaskets on late model bikes.

Pete

If they're available, I haven't seen them advertised.  (Anyone else in the USA know if they are available here?)  Pete, I saw your write-up on them and they appear to be the best valve cover gasket one could install on a big block Guzzi. 

If there's some way you can take paypal, I'd be more than happy to order a set thru you and pay for the gaskets and shipping. 

I'm not certain the valve cover gasket is part of the problem, but I'd love to install a set of gaskets that might end the worry of one blowing out.  I  still keep a 'heavy duty' green one taped to the inside of my HB 30 liter bag.

Bob