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Message |
    
Colin R. Ashton
New member
Username: crash
Post Number: 1
Registered: 10-2006
| | Posted on Tuesday, October 24, 2006 - 06:29 pm: | 
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I have a P66D Ser No 22B707 mounted in a 15Ft day boat aquired 12 months ago. Persistent problem of No2 (aft) cylinder oiling or sooting up afetr about 40mins running. Clean or replace plugs and away she goes again. No1 runs spot on, light tan clean plug. No2 runs slower than No1 when going solo. Had other intermitent faults so rewired, new coils, set points and timing, cleaned carburetter. Compression test is No1 110lbs, No2 120lbs, suspect it needs a decoke. What should pressures be? Any other ideas please before I start to take apart - Thanks} |
Tim Mulvey
Senior Member
Username: timmulvey
Post Number: 101
Registered: 05-2003
| | Posted on Wednesday, October 25, 2006 - 05:21 am: |
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The P66 manual shows compression as "6.1:1 overall" I think the conversion to PSI is to multiply by 14.6956, though that doesn't seem to equate with your readings.
Re the excessive carboning in cylinder 2 (rear of engine),I suggest that you may have a problem with the rear crankcase seal. As the seal deteriorates the oil in the petroil mix isn't sufficiently removed before the charge is released from the crankcase to the cylinder, hence the oil carbonising in the cylinder. If it very bad then there should be oil going out with the exhaust so remove the exhaust pipe and check for excessive oil. As it may be the rear seal it will be blowing oil into the rear section where the gearbox is fixed so you will only know for certain if you remove the gearbix and run the engine and look for oil weeping from the seal. If it was the front seal then it would discharge behind the flywheel and spread out the rear of the flywheel as the engine runs.
Anyway it's only a suggestion. Use modern seals if you want to replace it. You can get them from any bearing supply but there are a couple of extra hints which I'll tell you about if you want to know more. |
Peter Ogborne
Senior Member
Username: peterogborne
Post Number: 175
Registered: 09-2002
| | Posted on Wednesday, October 25, 2006 - 09:40 am: |
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I am sure Tim is correct ...but let us all know what the result is |
Colin R. Ashton
New member
Username: crash
Post Number: 2
Registered: 10-2006
| | Posted on Wednesday, October 25, 2006 - 07:05 pm: |
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Tim, Pete, thanks for that I have got hold of an original handbook to go with the engine. 6.1:1 by 14.7 is about right (88.3) that's what this book says, compression approx 85psi. Hence I think it needs the decoke because of the higher readings. Hope its not the seal as I see from the board this is an engine out job and complete strip, no small job!.
Tim I would be interested in your tips if you would like to e mail me.
I'll let you know what happens over the next few weeks, thanks very much. onwards and upwards. |
Tim Mulvey
Senior Member
Username: timmulvey
Post Number: 102
Registered: 05-2003
| | Posted on Thursday, October 26, 2006 - 05:30 am: |
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The cranckcase seals are probably the bronze ring type. The modern seals are far superior but you will need a short and long compression seal sleeve for the front and rear respectively. Also, the back of the collet onto which the flywheel fits needs a little machined off it. If in England you can get the sleeves from Fairways or else I can provide measurements to get then fabricated and the collet "reduction" measurement. Seals from a bearing supply - I can give you the reference numbers and then have look up tables for equivalents in other brands. Alternatively just get new bronze rings for front and rear from fairways or else get then made up from Phosphor bronze.
Compression seal replacement is a major job and you could create other problems as I have encountered eg damage the crankshaft keyway for flywheel key if you don't retighten the flywheel sufficiently - I have to weld the keyway edges with a copper key clamped in place then grind and file the keyway part of the crankshaft. Then I had to weld a crack in the flywheel collet as a result of it being damaged on the burred up edge of the keyway.
At the other end be careful you don't damage the nut that holds the clutch cone. You will need a tube spanner to remove it then a gear puller as the cone has two keys.
On removal of head studs I suggest you double nuts then and remove but build up of rust of studs may mean that you need plently of penetrol down the stud to soften the rust before you can extract the studs. Then remove the whole head and cylinder together as the head may be part welded onto the cylinder by rust at the water channels. This will avoid using a new gasket etc. Keep the head and cylinder full of frsh water at all times and do not remove either the expansion chamber water jacket cover plate, the small oval water jacket cover plate on the opposite side or the exhaust outlet.
Anyway that's enough for now. It will give you a taste for the job ahead.
I should add that there is a short cut to the job which is double nut and remove rear and front sections of the crankcase by removing the two front and two rear head studs and undoing the four crankcase stud nuts then slide each end off but you still need to remove clutch cone etc after removing the gearbox. |
Colin R. Ashton
New member
Username: crash
Post Number: 3
Registered: 10-2006
| | Posted on Friday, October 27, 2006 - 06:03 pm: |
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Tim, a quick question whilst I digest the rest of your info, why should I not remove the exspansion cover plate? (I was going to do this next as all the brass nuts are free).
PS The boat is on the river Thames do I still need the fresh water kept in?
Thanks - Colin |
Tim Mulvey
Senior Member
Username: timmulvey
Post Number: 103
Registered: 05-2003
| | Posted on Saturday, October 28, 2006 - 05:33 am: |
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Thre is no reason to remove the expansion chamber cover plate unless you are going to clean out the water galleries in the cooling chamber. It can be a lot of fiddling around to ensure that it is properly resealed. Further, you need to keep the cylinder wet while you do the seals but if you do want to clean out the water galleries then do it at the very end but simply if the engines not getting too hot then don't bother.
Also, I forgot to add that before you can remove the rear crankcase section you will need to remove the common water pump/magneto drive chain assembly as the chain is driven off a cog on the crankshaft. |
