Suzuki DT65 Crankshaft bearings question

3rdMarDiv

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I have a Suzuki DT65 06502 502849 65hp which I believe is a 1986 motor.
It has 3 cylinders.
Running on water muffs it seems great. Starts easily and goes into gears nicely.
When in the water, as soon as I place it into forward or reverse, it shuts down.
I have been told by Suzuki that this is likely due to bad bearings. I am in the process of tearing it down and opening the power-head.
​I have removed the flywheel and found the magneto plate to be clean and looking like new.

My questions are if the bearings are bad then would that cause the upper crank seal to be bad and there be oil (residue) leakage from the upper seal?
and, If the bearings were bad would that cause the crankshaft to have wobble?

Thanks for any assistance.
 

mphelle8vld

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It's a 1985 by the serial number. Is the motor new to you or was it running fine and now this problem has come up. Did a Suzuki shop work on your motor? Looking at your post, bearings would be the last thing I would check. I would start with compression check, clean carbs, check and adjust TPS. I use that powerhead and have the factory manual if you have any questions.

Just looked at an old post of yours, I would look at the operation and adjustment of the throttle position switch assembly and check that the timing is advancing just off idle.
 
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3rdMarDiv

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Thank you for getting back with me.

I was shown the motor running on muffs running great. Went into gears and prop turned as it should. I agreed with the owner to take it to a authorized Suzuki dealer for a pre-sale check. Took it to the dealer and was told the motor was in very nice condition, but needed carbs re-built, new temp sensor. They said it had great compression with 3-4 lbs difference. Good spark, etc. I bought the boat and motor. Later the dealer advised me that the jets were wrong for that motor. They ordered and installed new jets and rebuild kits for the carbs.

Months later they advised me that Suzuki advised them that the seals between 1&2 and 2&3 cylinders were most likely the problem.

No one at the dealership has ever opened up a power-head, so, I am reluctant to give them back the motor.

I have a Suzuki Tech Service book. Are the steps you mentioned in the book. I will look them up and see if it's something I can do. Thanks, any help is appreciated.

Do you know what would be considered good psi compression for that motor?

PS: I should ad that when on muffs I placed the motor into gear and accelerated to about 1/2 speed in both forward and reverse gears. Motor ran fine and prop spun fine.

When in the water when placed into either gear the motor stalls out immediately. Runs great in neutral.
 
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mphelle8vld

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My motor has 125psi on all cylinders, runs well at 5500rpm. The checks and adjustment of the TPS is in the service manual.

Can you describe in detail what the issue is, this post it sounds like it shuts off when put in gear with load. A post from last year made it sound like it was stalling at WOT out on the water.

Can you adjust the idle speed with the idle adjustment switch under the hood?

Do you have a timing light to check what the timing is at while idling in neutral?
 
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3rdMarDiv

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Problem is when in water and placed into gear the motor stalls and shuts off.

Q1: There is, from what I can see, a Trolling Speed Adjustment Mechanism that can speed up or slow the RPM,s. This is a black box on the side of the engine that has a switch with 4 settings and arrows indicating faster to slower.

Q2: I have a lazer Tachometer that shows in idle that the RPM is 1635 at the fast setting and 1594 at the slow setting. This is on muffs in the driveway.

What is TPS..? I will check that also.

Thanks for all your help.
 

Propwash79

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That doesn't sound correct. Correct me if I'm wrong,but if the seals are gone between the cylinders it won't run smooth. Sound like it might be a adjustment with the timing or the ignition part. I would disconnect the cables from the linkages in the motor and manual shift it into gear then give it gas, if it works then I might be the safety switch in the control box. I think you may have jump the gun but since your this far in then finish the rebuild or stop and put it back together.
 

mphelle8vld

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Q1: It sounds like the trolling speed adjustment switch is working but the idle should adjust between 700-900rpm with that switch. Q2: Not sure if your tach is giving you the correct reading.

If the Suzuki shop had your motor and rebuilt the carbs they should have adjusted them along with the TPS. If you have or can get an inductive timing light, connect it (one at a time) to all three cylinders to make sure you have spark on all cylinders. That motor will run on two cylinders on muffs but will die under load.
 

3rdMarDiv

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Thanks guys, this gives me more items to look into. I did not dissemble the motor. Stopped and put it back the way it was, Let me work on the suggestions you have made and I will post afterwards. Thanks so much, you guys are great.
 

racerone

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In gear on muffs on the trailer is still the same as nuetral.---The prop turns but is not doing anything !!
 

3rdMarDiv

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In gear on muffs on the trailer is still the same as nuetral.---The prop turns but is not doing anything !!


You know, I never would have looked at it that way...Thanks, that makes perfect sence...Zero resistance...

I have a friend coming over and have printed out the info supplied above...
 

99yam40

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You know, I never would have looked at it that way...Thanks, that makes perfect sence...Zero resistance...

I have a friend coming over and have printed out the info supplied above...

A boat and motor with a regular prop, tied to a dock or on a trailer while running in gear will have more load on it than if the boat was able to get up on plane.
best way to test a motor is with a test prop made for that purpose while on trailer or tied to dock where it is not going to move to see if it can spin up to the proper RPMs listed for that motor with that test prop.
 

3rdMarDiv

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I would disconnect the cables from the linkages in the motor and manual shift it into gear then give it gas, if it works then I might be the safety switch in the control box.

Took it over to the launch yesterday and disconnected the throttle cables and shift cable. Ran fine in neutral. Manual shifted into forward and it died. Tried several times attempting to manual increase throttle. Motor would run for maybe 3 seconds and die.

We double checked spark...OK
Double checked compression at 130 to 135 each...OK

Every time we restarted the motor we had to manual choke it.

The boat was on the trailer and I just read the 99yam40 post on using a test prop. I have a friend who runs a Prop Repair shop and will check on getting a test prop and try it all again.

My friend did place his hand over each carb to feel for suction and the top carb had good suction, but 2 and 3 did not. Don't know if that tells you anything.

I'll check on the test prop and get back, Gary
 

Propwash79

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Ok your heading in the right direction. I would skip the prop for now and find the idle screw on the carb and turn it 3/4 to 1 turn to bring it to a faster idle,not roaring idle but about 1000-1200 rpm and take it to the ramp and crank it in the water,let it warm up and then put it into gear, if it dies then???? If it holds good then back the idle screw back down to the original point and th n shut it off and repeat it again and if it shuts off then see what the tach shows far as rpm.
 

mphelle8vld

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Placing one's hand over the carbs is fairly subjective but if your friend is sure of his results then the labyrinth seal between 2 and 3 could very well be bad.
 

3rdMarDiv

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QUOTE=mphelle8vld;n10003783]Placing one's hand over the carbs is fairly subjective but if your friend is sure of his results then the labyrinth seal between 2 and 3 could very well be bad.[/QUOTE]

At one point when the Suzuki Dealer was out of options they did contact some Suzuki Guru (Regional Advisor ?) and that is what this person told them that the Crank Seal between 2 and 3 was bad.

I guess Suzuki has new seals used now in place of the ones in my motor that are better.

Man, my options here are not looking bright. If they open it up and find the seals aren't bad, I still pay for all the work they do unnecessarily...Time and Labor.

Thanks for all your help guys.

This may be a good motor to part out. I've been told the parts sell on eBay quickly and at good prices.

I took it off my boat and have replaced it with another motor. It's an a rack now.
 

mphelle8vld

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The seals on the early models did not play well with ethanol, they came out with a replacement and then around 89 changed to a sealed bearing. Nice that you were able to repower and get back out on the water.
 
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