1996 Speedster Cable Replacement And Major Cavitation Problem

[Ed Clark]

So, the second sea trial with The Beast was a complete bust. This was conducted on Saturday, 12/7/24. To stay on topic, you will recall that ventilation aka cavitation of one engine is the problem that this thread is attempting to address. The rest of this post is simply a sob story that you'll learn nothing from although you might find it humorous from a comic tragedy point of view. Just joking. Only saying that if you read the balance of this you aren't going to learn a lot about the subject topic.

So, here goes. As background, I should tell you that unlike SDC_MI's vessel, mine is a project boat that has been considerably used and abused by previous owners. We do have in common the ventilation issue. So, the plan that I was supposed to execute from my previous post was to order and install a new aftermarket "thru-hull fitting" on the starboard engine. I did receive same and it was beautiful in construction and dirt cheap. I pulled the s pump, driveshaft and boot only to discover that, well, it would be a waste to time to install the new fitting as the original seemed to be in perfectly serviceable condition. So, I reassembled everything paying special attention to ensure the boot/friction ring assembly were making a good fit. By the way, I did use an alternate boot that I had laying around in the parts pile.

You may recall that on sea trial one I also had a problem with the port engine in that it would pull to around 3,000 rpm then immediately bog as if running out of fuel and drop back to idle. So, I had refurbished the port carb with a kit and tested the pop off to 24 (should have been 26 minimum per spec) and called it a day in that department. I ran both engines dry for around 4 minutes and all seemed OK. I didn't want to bother running them on muffs again, but as you shall discover, perhaps I should have.

So, the night before the sea trial the temps had dipped to the mid twenties. When I went out to check the boat again before towing to the river I discovered that the forward/reverse cables (one for each engine) and the steering cable were frozen and their control handles couldn't be moved. In retrospect, this make perfect sense as the point the cables exit the stern is submerged iin operation and are bound to take on some water. However, it was a new one on me. I fear I got a little violent with trying to free them up including trying to defrost them with a heat gun. Well, nothing seemed to work so I tentatively wrote off the sea trial for the day.

In the afternoon, the sun had been beating down on The Beast for a couple or three hours and I decided on a whim just to see what was going on. Lo and behold, the frozen cables had defrosted. Really getting late in the day at this point but I was chomping at the bit so I ran through my quick checklist, hooked her up and an hour later I was at the river launch.

The day had warmed to about 40 at this point but the temps were already starting to drop for the day. There was only one other trailer at the launch. One of the die hard bass guys no doubt. Being alone, I used the old tie a lead rope to the pier walkway, back up and stop aggressively to launch the boat technique. I then coaxed the boat to the end of the pier and tied both bow and stern to cleats. The plan was to run the darn thing under power on both engines while statically tied to the pier. This as a safety precaution before I commenced a run on the river from which there might literally been no return depending on engine performance.

Ah, I must pat myself on the back for my wisdom such as it is. Read on. So, I board and start both engines. Both are idling very nicely and I allow them to warm for about 10 minutes or so while I revel in just what a great day this is going to be. Not! Read on. The first malady encountered was that the starboard engine would not rev. Why? Broken throttle cable. Probably my fault for jacking things around in their frozen state. But, doesn't matter. One engine out of the picture but that's the reason you have two, right?

Lo and behold I notice that the port engine is leaking water out of the top engine cover. I had been warned about this by the previous owner but had not witnessed it myself so wrote it off as him being a dope. Now we know who the real dope is. Not to be deterred since I had a functioning bilge pump (I hope) and I was bound and determined to run at least one engine on the day. Not! Same old bogging issue as before. As I tried to increase rpm's above idle, it would spin up a bit then bog right back down.

Crap! Well that's almost the end of the story, but not quite. Of course there was no way to load the boat by coaxing it back on the trailer with the aforementioned lead rope. Fortunately(?), I had foreseen this eventuality and had provisioned myself with a pair of sneakers for lower leg submerged work in icy waters. Good thing I did as there was a coating of mud on the ramp cleverly hidden under the waterline.

Anyway, the next day was warm enough and I had a gasket set in stock so I undertook to replace the cylinder head o-rings. This didn't go too badly. However, it was noted that while the bores and pistons looked fine, there was some distortion in the water jacket area of the rear cylinder. Also, the replacement gasket set provide one round o-ring as a replacement for the OEM square o-ring. So, if you had to guess, where would you say I got an immediate leak upon restarting the engine on muffs?

So, here's the path forward. The port engine is coming out for an eventual rebuild. I have a spare shortblock that shows good compression but I have never heard run that will be going asap. Also, of course, a repair to the starboard throttle cable is in the plan as well. Recall, that the whole point of this thread is to find a solution to the ventilation aka cavitation issue on the starboard engine.

Even colder weather coming as well as Christmas at this point. Still, I'm pumped to conduct sea trial number three. Best guess is the end of December for the next report. Sooner if weather permits and the back-up engine actually runs when installed.

 

[SDC_MI]

Ed,

I have made no progress on the issues of my own to date. I definitely feel for you as it seems you are going through a lot of struggles similar to my own. I was very curious about that thru-hull fitting you were going to install. I did a fairly thorough check of my hull when I had everything apart and that was one area I was concerned with. I couldn't find anything wrong with my hull and didn't even know the repair kits were a thing.

The carbon rings I purchased as replacements were not factory, but were a "heavy duty" aftermarket version. They seemed to be very high quality and everything went together as it should. There is what I would consider adequate pressure on the carbon ring as provided by the new bellows. The one assembly flaw I am aware of is that I may have gotten some grease on the face of the carbon seal which I later cleaned with brake-clean. I doubt this would be enough to cause my issues but maybe....

In reading your posts, one piece of advice I have read and would pass along is the danger of running the boats out of water for very long on the hose. It is fine for the engines, but apparently you can burn up your carbon rings without having water to cool them. I have run mine for a few minutes at a time out of water but again, I don't think that would be enough to completely kill the rings and cause my issues. After the amount of work I have put into replacing everything I am very discouraged by the thought of tearing it all back apart and potentially replacing parts again without ever actually using the boat.

My boat has never run without cavitation except in a couple short stints where I had to work very hard to get it on plane. At that point it seemed that once I finally got it moving I could continue to stop/start with less cavitation/aggravation. But that was short-lived and prior to me replacing everything. I was actually surprised as this boat came from the original owners who supposedly had everything factory serviced throughout it's lifetime.

You seem to have more motivation than I do currently to fight through this, along with weather that mostly allows you too. I hope you can find something that I could not and, in turn, help me to resolve my own issues. I'm actually surprised that some of the forum pros haven't chimed in to this thread. I've seen a lot of great advice come by the way of Dr. Honda and Mikidymac but I have not gotten anything in the way of responses here. There has been other support which is great and is exactly why we come here. Again, this is just another old toy that should be simple to fix but continues to test my patience.

-Sean

 

[Ed Clark]

So, it's the 28th of December and by this time I had hoped to have conducted a 3rd sea trial with respect to the subject topic but it wasn't to be. Not that I haven't been busy. You may recall that I acquired 2, 1997 Speedsters from separate owner's some time back and both were purchased with and questionable engines and even more questionable maintenance on the pumps. Oh boy! In fact, Speedster #1 simply had two engines and the propulsion gear thrown into the engine bay loose, a true basket case if I've ever seen one. Speedster #2 had everything apparently bolted in it's correct location and both engines would run, barely, in the driveway.

So, I patched Speedster #2 up with the proverbial tape and bailing wire and hauled it to the river for two separate sea trials. I've previously talked about the results from those so I won't beat a dead horse. In summary, following the second sea trial, my work list included repairing the broken (wasn't broken - another story) throttle cable on the starboard engine and the bogging and noise problem on the port engine. This just to get to the subject of this post which, in my case, is a severe cavitation aka ventilation aka "clutch slippage" issue on the starboard engine that reared its ugly head at the first sea trial. That goal remains the same and I had postulated in my last post that by this time I planned to have conducted sea trial #3 to begin to better diagnose the subject problem.

Ah, the devil is in the details as they say. I've been working all month just to try to put together two relatively healthy engines so I can get on with the cavitation thing. To date no joy. I'm not going to bore you with all the details, but I'll give a quick summary to give you the idea. Since my last post, I've pulled and partially disassembled the port engine. I used parts from some of the other engines to commission "engine #3" and installed it. It started and ran beautifully, or so I was thinking for the first five minutes. Then it locked up! So, I've partially disassembled it and still haven't gotten to the cause of the lock-up, although it is very much looking like a main bearing on the crankshaft of all things.

My last "spare" engine was one of the two contained with the dog's breakfast (as they say in Canada) of parts that was thrown into Speedster #1. It looks pretty good, but it's a 657X as opposed to a 717 and the gods only know what kind of shenanigans it will pull if I just try and throw it into service without tearing it down first.

So, all that to say that I've been working towards getting two relatively healthy engines installed so I can then pursue the reason I initially jumped onto this thread. I'm not quite ready to do this yet, but I'm just about at the point of sticking a new short block into the fray. Before I go down that path, I plan on completing the tear down on two engines I've got in the garage to access the condition of their crankshafts. By the way, both top ends of the two engines I've disassembled are pretty much junk. So, at least I'm going to be faced with one or more top overhauls. I'm up to that so long as the crankshafts are sound which is yet to be determined.

I'm at least getting to the point that I show no fear when it comes to jerking an engine out to have a look-see. To work on an engine in the boat is the farthest thing from a shortcut that I can possibly think of.

Anyway, hope everybody had a good Christmas and I'll post an update on progress in a couple of weeks or so. Cheers.

 

[Ed Clark]

Ouch! I got tired of fighting that port engine which has been standing in the way of getting on with the cavitation/ventilation issue. I've got engine parts from three separate engines lying all about my garage at the moment and a Speedster setting just outside that's going nowhere fast. So, I bit the bullet and today ordered a reman. engine from SBT. I am hell bent on getting this thing in the water before end of January to evaluate the cavitation. Wish me luck.

 

[burtshaver2021]

Best of luck

 

[treimche]

@SDC_MI sorry to hear of all your cavitation troubles. I just stumbled upon this thread and read through. When I bought my 1996 Speedster it also had really bad cavitation, but my buddy I bought the boat from informed me of this issue that I'd need to fix, along with getting the boat running after sitting for 7 years

One thing I would do when it was cavitating badly on the lake, was to open up the engine compartment and pull the bellows back just enough to let a little water in. The water would create a temporary seal between the worn out carbon seals and top hats, so then I could get the boat up on plane. If your bellows aren't very stiff and hard to move by hand, they should be replaced. It's also a good idea to use the thicker heavy duty stainless top hats from OSD along with new OEM carbon seals. This will put extra pressure on the carbon seals creating a tight seal. How long do you run your boat on the hose when out of the water? Just asking because if its more than a couple minutes you can burn up the carbon seals.

Any weeds or grass stuck to the driveshafts will cause cavitation too. Gotta try to keep them clean when on the water. But your case doesn't sound like a weed problem.

When you installed the new pumps with new wear rings (always use OEM wear rings), was there any interference between the the impeller and wear ring? They can be close enough to touch and its ok because the impeller will create the clearance needed quickly