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Dominick
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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How do check crankcase pressure on a 91 pro v 200 p200TLRP

Customer Question

how do check crankcase pressure on a 91 pro v 200 p200TLRP
Submitted: 12 months ago.
Category: Boat
Expert:  Jeff G. replied 12 months ago.

there is no way to check crankcase pressure. We usually spray carb cleaner, WD40 or some other fluid and spray around the crankcase half, carbs, intakes etc. If the rpm changes there is a leak.

Have you checked the reeds? Any signs of water? Were the idle tubes removed from the carbs and cleaned? New carb gaskets?

How are you determining #2 is dead at idle?

Have you done a spark test or run with a timing light on each cylinder?

Customer: replied 12 months ago.
There are no external crankcase or intake leaks. Done all the spray stuff. As I said in my initial description, I have pulled reeds and resealed intake. Just to be sure, I changed that reed unit with a good cylinder. Didnt change anything. I have also traded plug and coil with good cylinder with no change. Spark tester used and is strong. Compression is 110 on that and adjacent cylinders. No sign of water. Doesnt overheat. Its actually no 5 that is not hitting. I can tell because it does not change rpm at all when plug wire is pulled. All others do. I suppose my next step is to pull heads, but Im not optimistic because of the good compression. My only other thought was if the crankshaft sealing rings were leaking it might lower crankcase compression and cause an issue, but I dont really think thats likely either. Oh... on the carbs... they have been totally disassembled, cleaned and every passage blown out. I can spray a fuel mix or wd40 into the carb running and there is no change. Got to be something on the head side.
Expert:  Jeff G. replied 12 months ago.

Depending on the rpm pulling a spark plug wire may not tell you anything. What is your in and out of gear rpm?

Customer: replied 12 months ago.
Just fyi.... I am master ASE auto tech and have worked on motorcycles and outboards as well as autos for 40 years. Not saying my work is infallible, but I generally know my way around an engine of anynkind, but this one is being a little tricky
Expert:  Jeff G. replied 12 months ago.

Have you done a leak down test?

Customer: replied 12 months ago.
Cylinder doesnt hit below 1500 rpm. It may hit higher, not sure. Out of gear is 800, in gear 650. Yes I did a leakdown. All cylinders were about 10%. Very consistent. Thanks but think Ill move on. No sense taking up your time on stuff I already know.

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