Can the timing belt squeak on Merc 1500?

[Zac Penn]

On our last trip I noticed a squeaking noise (very similar to a squealing belt on a car) that wasn't a constant squeal but kind of like chirping/squealing. Sorry for the bad description. The noise didn't happen until we were already at our destination so no choose but to try and get back home. It made this noise when it was idling up to about 3000 rpm (maybe all the time but I couldn't hear it over the motor noise). We were about 6 miles from the boat ramp so I needed to try and get home at a reasonable speed (mostly around 4000 rpm). When we approached a no wake zone, about half way home, it would stall out on me if I went over 1500 rpm. It did this about five times when i tried to tweak out every last rpm in the no wake zone to get through it faster. I finally just settled for 1500 rpm for about 10 minutes and was hoping if I just straight punched it that it would work and get us home. Luckily that did happen and we made it home just fine.

My theory is that the timing belt may have jumped a tooth or something and messed up the advance. But what do I know. The fuel system is completely fine and all has been replaced so I know it isn't that.

Do timing belts squeal when they are bad or do they just break?
Could it be a bearing somewhere that is bad?

When I get back to the boat I will put on the ear muffs and try to do a video of the sound but that won't be until Monday.

Any ideas?

 

[emckelvy]

I don't see how the belt could squeal; it's rubber and is driven by cogs, so it would be extremely unusual for it to slip, unlike a "Vee" belt.

However, if either the upper or lower ball bearing in the distributor were going bad, they certainly could squeal and if they started to seize, could cause the belt to either jump or strip a cog.

Before you tear anything apart, check the belt alignment to see if it's jumped time. If you find that is has, be very suspicious of distributor problems. Pull the top cover off the distributor pulley and slip the belt off the pulley. Spin the dist. pulley; it should turn smoothly and quietly. If it feels rough, you need to disassemble the distributor for bearing R&R.

If you plug into your search engine "mercury distributor trigger replacement" you'll get plenty of results including this Youtube video in a foreign language, but pictures are worth a thousand words (in English!):

https://www.youtube.com/watch?v=LKeCX45HUpw

A service manual would be even better, check here at iBoats or at other marine sites on the 'net for those.

BTW in the vid he doesn't show how to get the screw-on cap loose; there are (2) locking tabs you'll see once you pry off the dist. pulley. The lock tabs are pried inward and then you can unscrew the cap (right-handed threads). Once you get the upper bearing out, you'll need a 3/4" long socket to loosen the nut that secures the rotor shaft. Note the rotor is permanently molded onto the shaft, Do Not attempt to remove it from the shaft, that's an $$$$$ mistake! I hold the rotor in a gloved hand, while using a small butterfly impact wrench on the 3/4" socket. Yours might just come loose with normal force from a ratchet.

Last little secret, the lower bearing is held in by a snap ring. This snap ring deteriorates, breaks, then drops down and gets swirled around like food in a blender. Guess what it blends up, you got it, The Trigger! Bam! there goes a $300 part because of a $.50 snap ring! So, replace that ring when you replace the bearings, and give it a thin coat of marine grease so it won't ever rust and break.

There ya go, time to go to work! HTH...........ed

p.s. if the dist. ain't the Squealer, something else is, and likely it's a bearing. Not good news there at all! In that case, take a compression test. After that, with the plugs out, turn the engine over with a 15/16" socket on the flywheel nut. See what it sounds like and go from there. G'luck!!!!

 

[Zac Penn]

Thanks Ed! I didn't think it was likely that the timing bet would squeal due to the tooth profile but I figured it was worth a shot A lot easier fix then a bearing issue somewhere hahaha. I will do some searching tomorrow but I don't know how far I will get. I have an extremely busy week at work so I have to prioritize. I will update when I get a chance.

 

[GA_Boater]

Had the upper bearing go out on mine. The belt would skip a tooth and the motor would die. After I figured out what was going on after a couple of times, I replaced the belt since it had to be stretched. I finally noticed as I putting the new belt on that the distributor shaft felt like gravel when I turned it. Ended up changing both the upper and lower bearings and not a problem since.

Pop the belt and see if the shaft spins smoothly - A quick and easy check, Zac. Mark the top of of the timing pulley and flywheel if the timing marks are gone.

 

[Zac Penn]

Okay I had a chance to take everything apart today and sure enough the bearings were pretty bad in there. The timing belt looked good and was not damaged at all. After I removed the bearings I figured I would try my luck at a local linear motion (bearing shop) store to see if they had these bearings. Sure enough they did and it only cost me $20 for both bearings and I didn't have to wait for shipping. I got everything all put back together and right before I could really get into the link-n-sync an afternoon store hit.

I don't know how accurate everything is in this video but i am using it for reference...
https://www.youtube.com/watch?v=eSk01fvCbec

Before the storm hit I started the process for the primary pickup adjustment at 5 BTDC and the first little paddle is moving the carburetor arm a few degrees too early based on the video. I loosened the two screws and adjusted the paddle as much as it would allow but it still seems to make contact a few degrees too early. However if I adjusted the distributor pulley one tooth over I think it would be too much of an adjustment.

Thoughts?

 

[Chris1956]

I looked at the video. I think that video makes a simple process much harder than it needs to be. I use a simpler process, much closer to what Merc recommends.

Remove the prop, remove the spark plugs and reinstall them in their plug wires and tape their bases together and ground to the block. Now, set the #1 piston to top dead center using a screwdriver. Use a dial indicator or caliper or even a steel ruler to measure between the piston top and the water jacket cove. Note the measurement and add .464 inches to it. Now turn the flywheel CCW until the piston backs off .464 inches from TDC. Set the timing pointer to read '464".

Install a timing light on the #1 plug wire. Advance the throttle in gear, ign on, until the carbs are about to open. This is idle pickup timing. Crank the motor by jumpering the starter solenoid. Note the timing on the decal. Adjust the brass collar to make the idle pickup timing 4-6* BTDC. Tighten the bolts with a 5/16" wrench.

Advance the throttle to full, and crank the motor. Adjust the max spark advance set screw to read 21* BTDC. Adjust the throttle stop to stop the carb opening, just as it hits the carb stops.

Reinstall the spark plugs and wires. Connect up a flusher and adjust the idle stop set screw and throttle cable to push the throttle closed when in neutral, and RPM is about 900-950. It will be somewhat less in the water.

Grease up the prop shaft and install the prop.

 

[Faztbullet]

You cannot find trueTDC with a screwdriver and time this way as it will be several degrees out. Use a dial indicator.

 

[Zac Penn]

Okay I obviously have something out of time because I could only get to 4000 max RPM and I have very little power. Either way i was able to use the boat on Thursday for some UNPRODUCTIVE fishing. The motor sounded great until the end of the day and then the noise came back. The upper and lower bearings were both replaced and the noise went away so i guess something is causing the bearings to fail? Here is a quick video of the motor idling while i was waiting to put the boat back on the trailer...

 

[Chris1956]

I hear a rattle or clink. Check to make sure the bolt holding the distributor pulley is tight. I needed to use locktite on it and the outer flywheel bolts, to keep 'em snug.

 

[Zac Penn]

Yeah it is kind of a rattle. I have to tear it apart again to check those new bearings so i will see if anything can move around in the dizzy. My buddy gave me a really negative thought saying it could be the upper crankshaft bearings but I am really hoping that is not the case.

 

[Zac Penn]

No Title

I found some time to break into this yesterday and the distributor bearings were top notch. Very smooth. Everything felt fine on the dizzy side of things so i decided to dig into the crankshaft side. I removed the stator and cleaned up everything, and then removed the timing pulley from the crank shaft, and I think I found my problem. In the attached picture I am pointing to the bottom part of the timing pulley. It is just pressed onto the the bottom of that assembly. When i removed the timing pulley that bottom part (technically a washer) was not attached, but it was resting down onto the crankcase. The grease around that area was very shiny, kind of like metal powder mixed with grease and you can barely see where the washer had rubbed on the crankcase and smoothed it out. I guess that was my problem because I pressed it back onto the pulley (like you see in the picture) and then put everything back together.

The noise is now gone! However i don't know how long before that washer pops loose again. There didn't seem to be a way to mechanically keep it in place besides just pressing it on.
Any tips on that?

As for the timing of everything...
I was WAY retarded which is why I had such poor performance.
Thank you so much Chris1956 for the detailed explanation on how to time it. I don't have a dial indicator but I do have a digital caliper gauge that I used to find TDC.

 

[Chris1956]

Check the parts diaghram, to see if it is an official part. I don't remember that washer on my Merc 1500, but it has been a while.

The issue with finding TDC, is that the piston reaches the top of the cylinder, and stays there for some degrees, as the crank turns. It is hard to choose the exact moment of TDC. I believe that is why Merc chose the .464" BTDC to calibrate the timing. Glad it worked for you....

 

[Zac Penn]

Chris I was trying to figure out why they used that number when I was reading your timing explanation but it made sense after i was messing with the motor. I was cursing and grunting for like 30 minutes trying to get exact TDC because the crank would move a couple degrees and the distance remained the same. The .464" BTDC make complete sense after you **** away 30 minutes trying to get TDC just right

I can't tell exactly if that is a factory part or not, but the parts diagram I think shows it as a solid piece. Maybe if the noise comes back I will look into a new part. But for now i just want to enjoy at least two weeks without having to work on the motor.

 

[Zac Penn]

Okay I went for a water test and it seemed to have more low end power than the last trip but I am still not able to get above 4300 rpm. It ran nice and smooth but it just didn't have any more power. It was just me and only 25 gals of fuel so it wasn't over loaded. When I first got the boat running I was able to get to 5500 rpm, with two adults and 55 gallons of fuel, before I started hearing that clanking noise and started messing with the distributor bearings.


Timing is set correctly.
Throttle goes all the way until the carbs stop opening.
Carbs are clean and I have no starvation symptoms.

Can you guys provide me with a checklist of things to look into? I am getting so frustrated with this motor that I am considering just getting rid of it for something newer.

 

[emckelvy]

Check and double-check your maximum spark advance again. Years ago I had one where the timing kept changing on me, along with erratic idling. Turned out that the cogged drive sprocket on the flywheel had cracked, then it was loose enough to rattle around on its keyway, eventually making a groove where the sprocket went back-and-forth as it pleased. Thus continutally changing the timing and causing a lot of hate and discontent!

You may want to take the flywheel back apart and very carefully inspect the drive belt sprocket, to make sure it's not doing anything strange. I'd imagine that you could keep the bottom retainer ring from falling off again, with a little Loctite Bearing & Stud Mount or something equivalent.

HTH............ed

 

[GA_Boater]

Use a punch and peen the edge in a few places to keep the retainer ring in place.

 

[Zac Penn]

I looked the flywheel over pretty good the other day, but I will check again. At least this time I will not need to mess with the timing marker so reconnecting everything should be quick and painless.

I will also recheck my timing.

Do you guys have any other ideas as to why my motor would not rev as high as it used to only a couple weeks ago?

 

[Chris1956]

Low WOT RPM can be caused by one cylinder not firing. They sound pretty good running on 5 cylinders. Take a look at the spark plugs. If one is very clean, it indicates water getting into the cylinder, killing any ignition.

 

[Zac Penn]

Okay is the 30th round of inspections hahaha

I put the timing light back on the motor and sure enough I wasn't paying attention and had the spark advance set to 27 DBTDC. I can only attribute this because the sticker on the flywheel said MAX spark advance so I must have forgotten about Chris' 21 DBTDC. I readjusted it so that my timing is 20.5 DBTDC just incase 93 octane gas is not high enough for 21 degrees.

I inspected all of the spark plugs and they are all looking the same.

While I had all the plugs out I went ahead and connected my CHEAP compression gauge ($25 from Harbor Freight) to see if all the cylinders were the same. To my amazement the compression was deal on for all 6 cylinders (Really good sign) but the PSI was only 80 for all 6. WTF... I watched the previous owner test it and all of them read between 148 - 152 PSI. How can I loose that much compression so quickly? If anything I am running over 50:1 and always 93 octane fuel.

Is 80 psi okay?

I am going to water test it agin this afternoon but if you have any more suggestions on things to check I would like to look at them before I go.
Thanks as always for your excellent help,
Zac

 

[Chris1956]

It is virtually impossible for all cylinders to wear the same, and therefore have the identical low compression. Your gauge is likely inaccurate.

The real spec for compression is for even compression across the cylinders, which you have. The motor is therefore good.

Regular unleaded fuel is fine for that 21* BTDC max timing. It will run fine on the E-10 fuel as well. An exact 50::1 mix will give the best idle, especially if you set the idle mixtures with fresh 50::1 fuel mix.