Do I buy this motor - poppet trouble?

[shakybuyer]

Hi all, thinking of buying an '87 Black Max 135 outboard. The seller says it needs a new poppet. When I asked him why he said it won't go above 3000rpm - will run slow and at lower speeds but can't get faster speed from boat. I am not a marine mechanic at all and wonder does this make sense and would a relatively inexpensive poppet replacement take care of this? Any other questions I should be asking? Thanks for any assistance - great forum!

 

[Texasmark]

Re: Do I buy this motor - poppet trouble?

The poppet is a thermostat bypass for midrange to WOT operation. It doesn't control rpms it responds to a change in rpms in terms of the volume of water passing through your engine block; higher speeds need more water. If your poppet weren't working you would/could get an OT alarm when over about 2500 rpms, but that's all.

However, if your engine has a protective feature where the engine rpms are limited in a high temp environment which some engines have to allow you to get home with a malfunction, then yes a stuck closed poppet could be your problem and I assume it would be accompanied by the OT alarm.....probably the OT sensor output goes to the alarm horn and to the module that limits rpms during a malfunction. I never worked on that engine and have no manual on it. However keep bumping this up and one of the guys that have will answer you .

Mark

 

[Dukedog]

Re: Do I buy this motor - poppet trouble?

Like he says, poppet has nothing ta do with it. Could be several things causin' this. First "guess", which is all it would be on a computer, is stator but not necessarily tha culprit. Unless its dirt cheap like it is ya might wanna get him ta have it fixed................jmo

 

[jbjennings]

Re: Do I buy this motor - poppet trouble?

Sadly, what a seller says is not always/usually correct. I would have to check compression and it would have to be perfect before I'd even consider it. You could have expensive electrical problems as mentioned,and a bad cylinder or two could cause low rpms as well. You could even have a fuel problem. If you can't work on it yourself, I wouldn't buy the motor even if it has good compression because you'd immediately have to add at least a couple of hundred and possibly several hundred bucks to the price in labor/parts costs to fix it.
JMO,
JBJ