'94 GT-40, loss of power in gear |
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AKhunter
Newbie Joined: June-19-2017 Location: Alaska Status: Offline Points: 20 |
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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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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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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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fgroce
Senior Member Joined: July-05-2016 Location: Georgia Status: Offline Points: 350 |
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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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FGroce
88 Ski Nautique For 28 years Now 2002 Ski Nautique |
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AKhunter
Newbie Joined: June-19-2017 Location: Alaska Status: Offline Points: 20 |
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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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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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Keenan, Could you expound on the above? Sorry, I'm not following what's happening. |
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AKhunter
Newbie Joined: June-19-2017 Location: Alaska Status: Offline Points: 20 |
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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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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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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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AKhunter
Newbie Joined: June-19-2017 Location: Alaska Status: Offline Points: 20 |
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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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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 10775 |
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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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AKhunter
Newbie Joined: June-19-2017 Location: Alaska Status: Offline Points: 20 |
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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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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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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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AKhunter
Newbie Joined: June-19-2017 Location: Alaska Status: Offline Points: 20 |
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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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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 10775 |
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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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AKhunter
Newbie Joined: June-19-2017 Location: Alaska Status: Offline Points: 20 |
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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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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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Eric of FFM would chuck up the input shaft on his rebuilds in his engine lathe for testing. |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 10775 |
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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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SNobsessed
Grand Poobah Joined: October-21-2007 Location: IA Status: Offline Points: 7102 |
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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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“Beer is proof that God loves us and wants us to be happy.”
Ben Franklin |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 10775 |
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I'm wondering what's been happening with this mystery.
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AKhunter
Newbie Joined: June-19-2017 Location: Alaska Status: Offline Points: 20 |
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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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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 10775 |
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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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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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I have a feeling it when past neutral into reverse? |
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AKhunter
Newbie Joined: June-19-2017 Location: Alaska Status: Offline Points: 20 |
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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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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 10775 |
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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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Duane in Indy
Platinum Member Joined: October-26-2015 Location: Indiana Status: Offline Points: 1578 |
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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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Keep it as original as YOU want it
1978 Mustang (modified) |
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AKhunter
Newbie Joined: June-19-2017 Location: Alaska Status: Offline Points: 20 |
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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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SHOBRONCO
Newbie Joined: August-14-2017 Location: Huntsville TX Status: Offline Points: 11 |
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My boat is having the same problem, wonder if the new transmission fixed the problem?
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 10775 |
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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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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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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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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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KENO - must be faster on the draw than me today
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SHOBRONCO
Newbie Joined: August-14-2017 Location: Huntsville TX Status: Offline Points: 11 |
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Thanks Keno and Dreaming. Started new thread.
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