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Author Topic:   Compression at 80 PSI--Time to Repower?

billmontauk posted 03-29-2004 08:20 AM ET (US)
This weekend put my 17 madetauk in lake for first time this year..Engine started fine while waiting for engine to warm up out of gear at about 1800 rpms tack gauge got filled with smoke and turned black. Realy scared me thought I was going to have to use newly mounted fire extingusher. After a while I re started the engine it would idle out of gear but when I tried to go to neutral it stalled out. 1985 70 hp johnson 80-85 compression on all cylinders, new impeller new plugs. Do you think I should just bit the bullet and re-power
Al_A_Buy posted 03-29-2004 09:49 AM ET (US)
Bill - Start with the carbs. Good chance that the fuel in the float bowls evaporated or deteriorated and gummed up the jets. Would work OK at idle, but when under load (in gear), they are not providing fuel. A carb cleaner in the fuel might work, but might need profession help. Also try fresh gas in case you have water in the tank...
As far as the tach is concerned, two possibilities - condensation / moisture built up over the winter and shorted the gauge or you have a problem with the regulator. Regulator problems can sometimes manifest themselves as funny tach readings. When my regulator failed last year, my tach would be fine up to about 3K and then would drop to zero. Replaced the regulator and all is well.
AL W.
Bigshot posted 03-29-2004 03:17 PM ET (US)
Try a different compression tester(screw in) and do it again. If she really is 80-85lbs....she bit the bullet herself.
billmontauk posted 03-29-2004 06:09 PM ET (US)
The commpression test was done with screw in gauge it was 80-85 this engine it toast.........What to repower with?
I used my 16/17 madetuck 60% lake 40% saltwater What engine do you experts suggest..Thanks Bill
TampaTom posted 03-30-2004 11:30 AM ET (US)
How was it doing last season? If you have consistent readings on all cylinders, I think your gauge reads low or the engine been worn out for a while. I doubt the compression dropped an even 30 plus psi on all cylinders at once. Remove and clean the carb(s)
Bigshot posted 03-30-2004 12:46 PM ET (US)
For $20 I would buy a gauge and try again.
As for what to buy.....a Suzuki/Johnson 70hp 4 stroke of course.
jimh posted 03-30-2004 09:51 PM ET (US)
If you have $9,075 I would get an Evinrude E-TEC 90-HP.
JBCornwell posted 03-30-2004 11:00 PM ET (US)
Hmmm. Three cylinders all going bad at the same time?? Not likely.
More likely: Guage, technique, engine temp, throttle position, number of cycles to measure.
80 to 85 psi represents a range of a shade over 6%. That is normally considered a good engine.
How does one go from out-of-gear to neutral?? Did it stall when you put it IN gear?
If you just want a new engine, go for it. You don't need to rationalize.
Otherwise. . . is it really making power on all three? Maybe not. Compression has nothing to do with that unless it is essentially zilch, which it obviously isn't.
You probably have carb or fuel supply problems, maybe a dead cylinder. .. lost spark.
If you are sure the engine is toast, I will take it off your hands. No charge.:))
Red sky at night. . .
JB
Chuck Tribolet posted 03-31-2004 12:11 AM ET (US)
Given the tach went up in smoke, you have an electical
problem for sure. Maybe it was the tach, but it smells more
like a problem under the cowling.

Chuck

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Author	Topic: Compression at 80 PSI--Time to Repower?
billmontauk	posted 03-29-2004 08:20 AM ET (US) This weekend put my 17 madetauk in lake for first time this year..Engine started fine while waiting for engine to warm up out of gear at about 1800 rpms tack gauge got filled with smoke and turned black. Realy scared me thought I was going to have to use newly mounted fire extingusher. After a while I re started the engine it would idle out of gear but when I tried to go to neutral it stalled out. 1985 70 hp johnson 80-85 compression on all cylinders, new impeller new plugs. Do you think I should just bit the bullet and re-power
Al_A_Buy	posted 03-29-2004 09:49 AM ET (US) Bill - Start with the carbs. Good chance that the fuel in the float bowls evaporated or deteriorated and gummed up the jets. Would work OK at idle, but when under load (in gear), they are not providing fuel. A carb cleaner in the fuel might work, but might need profession help. Also try fresh gas in case you have water in the tank... As far as the tach is concerned, two possibilities - condensation / moisture built up over the winter and shorted the gauge or you have a problem with the regulator. Regulator problems can sometimes manifest themselves as funny tach readings. When my regulator failed last year, my tach would be fine up to about 3K and then would drop to zero. Replaced the regulator and all is well. AL W.
Bigshot	posted 03-29-2004 03:17 PM ET (US) Try a different compression tester(screw in) and do it again. If she really is 80-85lbs....she bit the bullet herself.
billmontauk	posted 03-29-2004 06:09 PM ET (US) The commpression test was done with screw in gauge it was 80-85 this engine it toast.........What to repower with? I used my 16/17 madetuck 60% lake 40% saltwater What engine do you experts suggest..Thanks Bill
TampaTom	posted 03-30-2004 11:30 AM ET (US) How was it doing last season? If you have consistent readings on all cylinders, I think your gauge reads low or the engine been worn out for a while. I doubt the compression dropped an even 30 plus psi on all cylinders at once. Remove and clean the carb(s)
Bigshot	posted 03-30-2004 12:46 PM ET (US) For $20 I would buy a gauge and try again. As for what to buy.....a Suzuki/Johnson 70hp 4 stroke of course.
jimh	posted 03-30-2004 09:51 PM ET (US) If you have $9,075 I would get an Evinrude E-TEC 90-HP.
JBCornwell	posted 03-30-2004 11:00 PM ET (US) Hmmm. Three cylinders all going bad at the same time?? Not likely. More likely: Guage, technique, engine temp, throttle position, number of cycles to measure. 80 to 85 psi represents a range of a shade over 6%. That is normally considered a good engine. How does one go from out-of-gear to neutral?? Did it stall when you put it IN gear? If you just want a new engine, go for it. You don't need to rationalize. Otherwise. . . is it really making power on all three? Maybe not. Compression has nothing to do with that unless it is essentially zilch, which it obviously isn't. You probably have carb or fuel supply problems, maybe a dead cylinder. .. lost spark. If you are sure the engine is toast, I will take it off your hands. No charge.:)) Red sky at night. . . JB
Chuck Tribolet	posted 03-31-2004 12:11 AM ET (US) Given the tach went up in smoke, you have an electical problem for sure. Maybe it was the tach, but it smells more like a problem under the cowling. Chuck