Got a buddy that has a 2010 36 ProDrive that started loosing power Saturday morning. Got so bad he had to idle back to ramp. Will get WOT without a load but put in in gear and nothing.

What he has changed are coils, diod, complet carb job, check valve lash, plugs. NOthing changed. Took the motor over the HW Marshal and the guys did the carb again first. Checked the coils/diod, compression was 150 both sides but the leak down test they said have 90% lose. What gives?????

Motor has 180+/- hours...

What would casue the leak...valves....rings....head gasket.....

Anyone seen this????

If he doesnt just put a new motor on it today we are going to check the valves to see if they are burnt.


If anyone here in Longview is Dr Motor Head and wants to look at it let me know. Who around here could do a valve job?

Later
James

You can lapp the valves in (if they aren't burnt/damaged, even then you can lapp the new one's in when you get them). It's very simple. Only reason you need to take it somewhere is if you need the seats cut, which I don't think you should. Are you sure they did they leak down properly? That sounds quite a bit out of the norm, but I have not done very many myself.

I'm not a pro, but I know a little bit. If you get over in the dallas area I wouldn't mind looking at it for you. Gary (DB8) is over this way also and is the best I know of in these parts, but I think you'd have to wait till after the season to catch up with him.

*boatdr beat me to the punch...ordering a new set of heads is an option as well.

New motor on the way....should b in Friday.

.

does ur buddy want to sell the heads off the old motor?

Yea cause I need them

new valves and a lapp job would have been cheaper

Well. in reality, you have to remember what these engines were originally designed for - lawn and gardening... They were never designed to turn 4500 - 5000 rpms as the mud out-drive requires. When you take an already weak platform such as the any of the current vertical or horizontal "air-cooled lawn engines" and raise their compression (this creates high heat levels which the engines cooling system (air) isn't designed for. Heat, by far is an air cooled engines worst enemy!), add a high lift/long duration cam. Adding one of these will kill the engines low rpm torque which is where these engines were designed to run. Now you have heat + an engine making more power at much higher rpms on a weak platform. ...hmmm this ain't look 'in good... On top of that a large air throat for even more power. What we've essentially created here is a time bomb or grenade engine. These engines simply cannot and will not ever be able to sustain the abuse a mud motor must contend with. I can guarantee you that your partner will be buying another engine in roughly 150 -200 hours.

The reason I know this stuff, I've been involved with hotrod VW's for many years and like your mud motors, the VW type 1 - 4 engines are also an air-cooled engine. But, the platform is not near as weak as what ya'll are dealing with. And the VW engine when adding high flow/high compression heads, high lift long duration cams, roller rockers, high spring valve pressures, high rev conrods etc, etc, etc... I've seen these engines let go of a conrod at 10,000 rpms and let me tell ya, there isn't much left to salvage after that.

So I'm a little familiar with air-cooled engines to say the least.

My guess would be over rev 'ing the engine creates more heat and if i'm not mistaken, they look burnt on the bottom side of the head (vertical shaft engine) where the heat is higher.

Whatever you do, just make sure you're buying an engine or heads that have high quality stainless or forged valve seats and valves installed. That will greatly help the situation.

Anyhow, favorite show's on now... I'll be around for questions.

Thanks