First Time Timing Belt Change F250

[No Bail]

So I finally got the old timing belt off. Very tight even after pinning the tensioner with a 5mm pin. I tried to put the new belt on using a rubber band to hold the belt on to start (tip from Sim on other site). No go.




So what is the secret to getting this belt on?

After the flywheel, Does it makes sense to start in the order, 1,2,3,4 on my photo? I'm trying to not turn anything out of alignment but I bumped 4 and it rotated about 30°. Hopefully didn't harm anything.




I'll try to get the belt on tomorrow, after renewing my patience.

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[Donnie Coulsting]

I have the same engine and I replaced mine last year and didn’t have any issues. I did discover that the belt tensioner needs to be fully rotated out of the way. Don’t force it, just keep pressure on it and it will slowly rotate. This should give you enough slack. You can find a video on YouTube.

[oldmako69]

I will second the YT Vid. Born Again Boating, I think. He walks you through the whole process on a 6 cylinder F Series Yam.

He takes particular care to describe the belt tensioner and how to release its tension and not bust it. Perhaps you've already seen this. I only post this for the next guy considering the job. Mine engines are at 900 hours so I'll be attempting this winter or next spring.

[No Bail]

Thanks for the replies. My 5mm Allen wrench was getting held but the tensioner was not open enough to put that Allen wrench deep into the tensioner. Once I waited with slight pressure for 3 minutes I could seat the Allen wrench.

I'll get another chance. When I went to put on the flywheel, it lined up TDC and the right side cam showed centered on the marks. The left side cam showed off 5°. I must have turned it slightly when putting the belt back on. So now I'll do it again to correct that 5° error.

[No Bail]

So I need to know how close is good enough on matching marks on the cam. I'll include a photo but you will have to zoom in to see the marks. The starboard cam is right on, the flywheel is right on at TDC. That pesky port cam moves everytime I put the belt on.

Will this measure of being off by 1 or 2° blow up the engine?

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[fairdeal]

Here's what Rodbolt posted some years ago:



Note also that his method includes a step
that AFAIK is not mentioned in the Yamaha Service Manual:
removing an idler to actually provide slack to position the belt

[No Bail]

I finally got the starboard engine all buttoned up and went to test the engine with a 100 gallon tank. Of course I had lost the bung. I grabbed a foam plug I keep on board and was able to test the engine. She ran fine after I pumped the bulb enough to get cramps in my hand.

Now for the oddity, the port engine will not raise, will not turn over and the Yamaha gauges do not work. Everything else on the boat works.

So what did I do? Earlier on the 12th I had a new plastic & canvas job done. I raised both engines to prepare for that tow. I had not finished the starboard engine so fitted the cowling on for the hour drive.

What did I mess up? I'll have to see what I've unplugged on the port engine as I was preparing to change that engines timing belt.

[No Bail]

So it is the battery bank. Found the cause.
During the 40 mile move some water shifted to the bow, turning on the bow bilge pump. It stuck on. Completely drained one set of batteries while at the upholstery shop during 4 days. Engine raises fine on all battery settings.

Those 2 batteries are nearly toast. Not sure I can get them to charge. Northstar group 27 AGM batteries.

[99yam40]

does not hurt to try to charge them on an old school trickle charger just to see .
the newer smart chargers will probably not even try if they are that low

[No Bail]

Just to follow up, I used the trick of hooking up a good battery to the old battery via jumper cables and then putting the charger on the good battery. All my batteries are OK and test good. I'm relieved.