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'94 GT-40, loss of power in gear

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Post Options Post Options   Thanks (0) Thanks(0)   Quote AKhunter Quote  Post ReplyReply Direct Link To This Post Posted: June-20-2017 at 12:54pm
Originally posted by Bri892001 Bri892001 wrote:

Wondering if it's something in or around the distributor. I'd check to see if you have any kind of excessive wobble or anything like that. You would do that with the cap off and holding onto the rotor portion and trying to move it around.

It seems funny that it's going through caps and rotors that fast, wondering if the act of replacing those items is brushing up against something that is loose/faulty and temporarily fixing it.

I'll check. This time I replaced the entire distributor because due to two striped out threaded holes. I figured that was easier than trying to install 8-32 helicoils.
Are you suggesting something in the engine's timing gears, or something outside the engine case?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bri892001 Quote  Post ReplyReply Direct Link To This Post Posted: June-20-2017 at 1:21pm
I was thinking the distributor itself, but since you already replaced that, that covers that idea.

When an engine is under load, any thing that is "shaky" as far as electrical connections related to the ignition is more apt to act up.

Of course, any fuel starve problem, timing problem or vacuum leak is also more likely to cause problems under load.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fgroce Quote  Post ReplyReply Direct Link To This Post Posted: June-20-2017 at 7:05pm
Don't forget the module on the heat sink, they were prone to failure. May have been why the put it on a heat sink instead of the distributor like Ford did. If he is getting a skip scan the computer for codes, KOEO and KOER and there are several other balance test you can run to narrow down the skip.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AKhunter Quote  Post ReplyReply Direct Link To This Post Posted: June-21-2017 at 1:46am
I got the engine back in and did a test run. Almost the same as before, but after adjusting the idle up a bit, the stalling on shift is cured. On a whim, I powered it up in reverse and I get full power?!! This new piece of info seems to point back to the transmission again?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8122pbrainard Quote  Post ReplyReply Direct Link To This Post Posted: June-21-2017 at 4:40am
Originally posted by AKhunter AKhunter wrote:

On a whim, I powered it up in reverse and I get full power?!! This new piece of info seems to point back to the transmission again?

Keenan,
Could you expound on the above? Sorry, I'm not following what's happening.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote AKhunter Quote  Post ReplyReply Direct Link To This Post Posted: June-21-2017 at 2:17pm
Originally posted by 8122pbrainard 8122pbrainard wrote:

Originally posted by AKhunter AKhunter wrote:

On a whim, I powered it up in reverse and I get full power?!! This new piece of info seems to point back to the transmission again?

Keenan,
Could you expound on the above? Sorry, I'm not following what's happening.

At the beginning of the thread, my engine was pulled, and transmission removed from the engine. I thought I was chasing a timing or timing advance issue. Everything I could see seemed to point towards timing advance issue. I had not pulled codes properly per the Pro-Boss GT-40 service manual before removing the engine because I hadn't found the manual prior to removing it. Another factor in my decision to follow the timing issue is that trying to get my current transmission overhauled would take close to a month considering my location. That would make the boat unusable for the rest of the camp season. I guess I was hoping that I might find an answer in the engine that I could repair before the end of the camping season. So, I reinstalled it all, checked my timing, and adjusted my idle up. I was about to start pulling codes, when I decided to try reverse. That's something I should have done before I pulled the engine in the first place. Reverse worked fine, plenty of power, and the engine ran great up to 3,000 RPM. I couldn't run higher than that because the prop tries to cavitate if I run it higher.

If it runs well in reverse (yes, I was in the lake when I ran it), I know that the engine is developing torque. The spark advance seems fine, I watched it with a timing light as it ran, both in neutral and reverse. In forward, the engine struggles so much I can't get a good reading on it. It seems to me that the fact that it runs well in reverse and neutral, under torque and unloaded says that the engine is fine, and the problem is in the transmission. The transmission manual (PCM 40A) says that it has separate clutch packs for forward and reverse. I'm wondering if I damaged the forward clutch when I slammed it into neutral from 2,000 RPM. While the engine was out, I did check the prop shaft and bearings. They spun smoothly with no sign of wobble or binding, so I'm pretty sure I can say that there is no problem back there.

What do you all think? Am I on the right track, or am I following a rabbit trail?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dreaming Quote  Post ReplyReply Direct Link To This Post Posted: June-21-2017 at 2:55pm
out on a limb here... Since this is a GT-40, I am not sure how the interface between engine RPM and Fuel delivery is made, but here is something to check anyway....YMMV

- If the engine is in neutral, and revs fine, but struggles under load, I too would have assumed timing advance originally.   Since you feel that you have vetted this angle, I would be looking into fuel delivery.   It seems to me that if the engine was getting a lean mixture of fuel, under load, it would cause a problem similar to what you might be experiencing. A lean detonation (or a malfunctioning knock sensor) could cause the ECM to retard the timing severely to protect the engine components... Sensors mustplay a big roll in the fuel delivery process, as would the ECM, which is known to have problems in these boats.   There does seem to be a work around for the ECM, so if that is the issue, you'll be on the cutting edge of the fix.

    The transmission seems like a reach to me.   Is there any way you could swap out a transmisision, either throw yours in a different boat, or pull in a known good one and see if the problem persists? that would focus your troubleshooting or give you a good idea of where to go next.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AKhunter Quote  Post ReplyReply Direct Link To This Post Posted: June-21-2017 at 3:59pm
Originally posted by Dreaming Dreaming wrote:

out on a limb here... Since this is a GT-40, I am not sure how the interface between engine RPM and Fuel delivery is made, but here is something to check anyway....YMMV

- If the engine is in neutral, and revs fine, but struggles under load, I too would have assumed timing advance originally.   Since you feel that you have vetted this angle, I would be looking into fuel delivery.   It seems to me that if the engine was getting a lean mixture of fuel, under load, it would cause a problem similar to what you might be experiencing. A lean detonation (or a malfunctioning knock sensor) could cause the ECM to retard the timing severely to protect the engine components... Sensors mustplay a big roll in the fuel delivery process, as would the ECM, which is known to have problems in these boats.   There does seem to be a work around for the ECM, so if that is the issue, you'll be on the cutting edge of the fix.

    The transmission seems like a reach to me.   Is there any way you could swap out a transmisision, either throw yours in a different boat, or pull in a known good one and see if the problem persists? that would focus your troubleshooting or give you a good idea of where to go next.

I can check that, but how could I be getting normal power in reverse, but not forward if that's the issue?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: June-21-2017 at 4:05pm
Dreaming He says it runs under load in the water in reverse. He quit at 3000 rpm due to the prop.

What I'm wondering is how you put it into neutral at 2000 rpm originally without having some kind of "war of the cables and linkages"

With a single lever Morse that's a hard thing to do without breaking or bending something.

Do both cables extend and retract smoothly the way they should?

We're not gonna see you on an episode of Yukon Men sometime soon are we?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AKhunter Quote  Post ReplyReply Direct Link To This Post Posted: June-21-2017 at 4:21pm
Originally posted by KENO KENO wrote:

Dreaming He says it runs under load in the water in reverse. He quit at 3000 rpm due to the prop.

What I'm wondering is how you put it into neutral at 2000 rpm originally without having some kind of "war of the cables and linkages"

With a single lever Morse that's a hard thing to do without breaking or bending something.

Do both cables extend and retract smoothly the way they should?

We're not gonna see you on an episode of Yukon Men sometime soon are we?

I'm not sure why the cables didn't fight each other? They didn't seem to, I can't find anything out of place/bent/broken in the cables and linkages, and both run smoothly. There isn't much travel of the throttle cable between 2,000 and idle and there is a bit of slop in the end of my throttle cable/throttle lever balljoint. It was the throttle lever that stuck, and as soon as I moved the offending cable, the lever snapped back to idle.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dreaming Quote  Post ReplyReply Direct Link To This Post Posted: June-21-2017 at 6:57pm
Originally posted by KENO KENO wrote:

Dreaming He says it runs under load in the water in reverse. He quit at 3000 rpm due to the prop.[/IMG]


fine, go ahead and cut off my limb

I saw that he was running it in reverse, but missed the 3000 RPM issue. Are the Trans's geared different in reverse?   Not that it would solve the problem, but the motor loading would be different
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AKhunter Quote  Post ReplyReply Direct Link To This Post Posted: June-21-2017 at 7:45pm
Originally posted by Dreaming Dreaming wrote:

Originally posted by KENO KENO wrote:

Dreaming He says it runs under load in the water in reverse. He quit at 3000 rpm due to the prop.[/IMG]


fine, go ahead and cut off my limb

I saw that he was running it in reverse, but missed the 3000 RPM issue. Are the Trans's geared different in reverse?   Not that it would solve the problem, but the motor loading would be different

Should I be worried about cavatating @ 3,000 RPM in reverse? I thought that would be normal. 3,000 RPM in reverse moves the boat rather fast and plows up a large wake. I was worried I'd swamp the boat with the wake if i pushed it much harder. I can't imagine a time when I'd want more thrust in reverse.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: June-21-2017 at 7:52pm
3000 in reverse means it'll handle some load.

The 1.23 to 1 PCM's have a reverse ratio of about 1.8 to 1 so yes it's different but I don't think that should change engine loading enough to let it run in reverse but not want to move it at all in forward.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AKhunter Quote  Post ReplyReply Direct Link To This Post Posted: June-21-2017 at 8:09pm
Originally posted by KENO KENO wrote:

3000 in reverse means it'll handle some load.

The 1.23 to 1 PCM's have a reverse ratio of about 1.8 to 1 so yes it's different but I don't think that should change engine loading enough to let it run in reverse but not want to move it at all in forward.

Is there any way to test the transmission before I before I drop 2.5k into a new or rebuilt one? I don't want to find out afterward that it wasn't the problem after all.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8122pbrainard Quote  Post ReplyReply Direct Link To This Post Posted: June-21-2017 at 9:06pm
Originally posted by AKhunter AKhunter wrote:


Is there any way to test the transmission before I before I drop 2.5k into a new or rebuilt one? I don't want to find out afterward that it wasn't the problem after all.

Eric of FFM would chuck up the input shaft on his rebuilds in his engine lathe for testing.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: June-22-2017 at 6:53am
If you want to spin the transmission in forward why not run the boat on the trailer either disconnect the shaft from the transmission or get the cutlass bearing good and wet with a hose

I think I'd disconnect the shaft if you're gonna do this for a while so you don't accidentally run the shaft with the cutlass dry (and you won't chop up any stray animals or people that get too close to the prop}

Then supply cooling water to the engine/trans cooler with a hose and run it.

You can shift from neutral to forward/reverse and see what happens with no load on the engine/transmission. Maybe everything spins freely with no noise/problems and you can rev it up or maybe it will spit and sputter and make funny noises and not want to rev up at all.

Basically just like spinning it on a test stand with no load

You could also shift the transmission with the cable disconnected and rev the engine with the throttle cable disconnected to rule out linkage/cable issues.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote SNobsessed Quote  Post ReplyReply Direct Link To This Post Posted: June-22-2017 at 8:07am
If the tranny is binding/dragging, wouldn't it get really hot really fast?

Maybe measure temp rise for a test.

I vote for the binding shifter/cable theory, since we already know if failed to start with.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: June-26-2017 at 9:30pm
I'm wondering what's been happening with this mystery.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AKhunter Quote  Post ReplyReply Direct Link To This Post Posted: June-28-2017 at 12:27pm
Originally posted by KENO KENO wrote:

I'm wondering what's been happening with this mystery.

I'm waiting for a new transmission. When I finally got the tranny oil plug out (Snap-On easy out and a 3/8 breaker bar) I found a fair bit of superfine non-magnetic powdered metal in the oil. It kinda looked like a maroon metallic paint. I'm about 98% sure that this is the problem. This winter I'll probably rebuild this tranny for a spare or sell- but mostly just to satisfy my curiosity. The new one is a conversion kit to a newer modle, I think the transmission shop said that it was a PCM-80 A?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: June-28-2017 at 12:49pm
I guess I'm not wondering anymore., on second thought I guess I'm wondering how going to neutral damaged it but maybe you can figure that out if you take it apart.

Sounds like you're describing clutch plate material in the fluid

Give an update when the new one is in
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8122pbrainard Quote  Post ReplyReply Direct Link To This Post Posted: June-28-2017 at 12:53pm
Originally posted by KENO KENO wrote:

I guess I'm not wondering anymore., on second thought I guess I'm wondering how going to neutral damaged it but maybe you can figure that out if you take it apart.

Sounds like you're describing clutch plate material in the fluid


I have a feeling it when past neutral into reverse?


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Post Options Post Options   Thanks (0) Thanks(0)   Quote AKhunter Quote  Post ReplyReply Direct Link To This Post Posted: June-28-2017 at 1:15pm
Originally posted by KENO KENO wrote:

I guess I'm not wondering anymore., on second thought I guess I'm wondering how going to neutral damaged it but maybe you can figure that out if you take it apart.

Sounds like you're describing clutch plate material in the fluid

Give an update when the new one is in

It might be clutch plate powder, but I have my doubts. When I separate the powder in a filter it has a yellow hue to it like its brass or bronze. Harbor Marine's transmission guy says that there are bushings made from both in this unit. I'll keep you guys posted, and if I remember, maybe I'll even resurrect this thread when I split the old tranny to rebuild. Another bit of interesting info, I asked about the maintenance history of this boat, and I got funny looks and questions about where the drain plug was located when I asked about transmission oil changes. I think the oil is still whatever Correct Craft put in it in '97
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: June-28-2017 at 1:45pm
You've also got sintered bronze clutch plates Half of the fwd plates are steel and the other half are sintered bronze.

When they slip enough the wear particles end up in the fluid
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Duane in Indy Quote  Post ReplyReply Direct Link To This Post Posted: June-28-2017 at 8:25pm
I have to go with KENO on this one.   Bushings in the tailshaft are very unlikely to have worn out.   Forward clutch plates.
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Originally posted by KENO KENO wrote:

You've also got sintered bronze clutch plates Half of the fwd plates are steel and the other half are sintered bronze.

When they slip enough the wear particles end up in the fluid

Ok, I didn't know that's how they built the clutch plates. So my "rebuild" of that transmission may be as simple as replacing the clutch pads or assemblies and flush/replace 10 year old ATF fluid? I guess I won't know until I start tearing it apart.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SHOBRONCO Quote  Post ReplyReply Direct Link To This Post Posted: August-14-2017 at 2:13pm
My boat is having the same problem, wonder if the new transmission fixed the problem?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: August-14-2017 at 5:03pm
If I was you I'd start a new thread describing your symptoms because AKHunter hasn't logged in since June 30th.and not all loss of power problems turn out like his
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dreaming Quote  Post ReplyReply Direct Link To This Post Posted: August-14-2017 at 5:04pm
Hi SHOBRONCO,
   Not going to get many responses jumping on to an old resolved thread, but we'd be happy to help.   Welcome to the site, start a new thread, tell us about your boat, what engine and configuration, year etc, and what symptoms you're having.    we can walk you through the process of troubleshooting so you don't drop 2k on a trans and have the same issue as when you started.    these boats are pretty simple creatures, so some troubleshooting usually will help point out the real issue.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dreaming Quote  Post ReplyReply Direct Link To This Post Posted: August-14-2017 at 5:12pm
KENO - must be faster on the draw than me today
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Thanks Keno and Dreaming. Started new thread.
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