Motor floods at idle when trimmed all the way down

[imported_bucketmouth]

This could be a rather long message. I have a 80 HP Merc ( Blue Band) Serial # 6234595. I had the motor rebuilt. The shop apparently could not get the motor to idle and called the Mercury technician down to look at the motor. After everything was said and done they determined that the block was "mismatched" and they could not get the extra 4 degrees of timing needed on the triggers. The shop contacted CDI to see if there could be a special made trigger and it was said that it could not be done. The motor is a Hard Start. When it is started the motor barely needs to be in the water and fast idled and choked. After idling for 4 minutes ( timed) you can gradually bring the controls to idle. If in idle and you trim down the motor, it wants to load up on fuel and die. If you idle up with the motor down or raise the trim up the idle speed picks up. The motor ran good in the water the day before yesterday, but stalled on me and my boys on Sunday. I was told by my brother in law who owned the boat before me that the floats may be off a little. Can someone point me in the right direction? I can give you more specifics on the motor but I feel like I have rambled enough for now.

Thank You

 

[Laddies]

Re: Motor floods at idle when trimmed all the way down

It sounds like the bores are not true and the rings are not seating, if it was not rebored at the time of repair I would say there is a 90% chance thats the trouble. The rest of thier story is crap trying to cover thier A$$es. If it had a miss matched block it would have not run right before, why was it torn down too begin with. If this sounds familier then tell them you can always take it to anouther shop and see them in court.

 

[imported_bucketmouth]

Re: Motor floods at idle when trimmed all the way down

First off, Thaks for the reply lads. At the time of inspection at this particular shop. I am looking at the bill and quoting what specs I can read or decipher. The leakdown test was as follows. #1 40 percent #2 85 percent # 3 65 percent and # 4 40 percent.
The compression beforehand was 130 125 95 125 cylinders 1 - 4 respectively. all cylinders were bored 040 installed new pistons & rings. new trigger, water pump new powerpack. It also says " pulled and chambered reed blocks on all to new specs. Most of this is relative to me since I do dabble with vehicle motors from time to time. But this shop which is rather large and does a high volume business first told me that the block did not come clean at 030 and they were hoping that 040 would get it and if not then the block would have to be re-sleeved. i have no idea what to do as far as legalities are concerned> they only charged me for parts and the out of house machining of the block( which has done work for me personally and i feel confident in their work and even called them to let them know that they were working on my motor. The total for this job came in right at $ 760.67. Tell me what you think as that is everything off of the repair bill. Other than that the Mercury services tech checked out and believes that the block is mis- matched.

 

[Laddies]

Re: Motor floods at idle when trimmed all the way down

Lets try to take this one point at a time, you have given us some good info now. Was this shop a Mercury dealer? Yes, with the compression figures it had some internal problems, anything from stuck rings to scored cyl. they opted for a rebore. so lets start there.
1. what was the engine taken in for orginally?
2. the fact that they changed the trigger and switch box in a rebuild shows that they are parts changes not mechanics (someone grasping at straws)
3. the spark advance thing is less than nornal at idle you are running at 4 to 8 degrees spark, that is advanced to 27 degrees at WOT. (so if the timing is off at either end it is because the engine needs to be synchronizined, which is a norrnal part of an rebuild)
3 there are no new reed block spec. and when aligned properly on assembly no chamfering is needed
4. if bored to .040 then they had to use wisco pistion which require special fitting and break in.(was that done correctly)
5 both boring and resleeveing are common pratices in service shops and should give you like new running when done properly
6. the amt. of compession in a 2 cycle engine is not as important as it being equal (120 is wonderful and all compression is reliant on the fuel oil mix the more oil the more compression)
7. if the crankcases are mismatched, why didn't the problem show before and why didn't they notice it on teardown ( if the crankcases are leaking they can be ck easily by spraying with WD 40 or carb cleaner)
8. the hard starting and the poor idle still point at unseated rings (especially if every thing on the outside has been setup right) the only other thing that gives those problems would be bad reeds which should have been checked on assembly
8. even if it sounds like I think the shop is not the best service shop in the world that may not be true. We all make mistakes and have worked in shop with less that quialfied people. This shop is showing they are concerned by not charging labor (I bet you would rather paid the labor and had a properly running engine) but they toke the job and if they can't repair it they should either send it out or offer or pay to get it right. We got into a mess back in the early 70s on a 115 that was were simular, had to get a factory rep to look at it when he said it was not bored properly we said BS and he said if it don't fix it I will pay the parts and labor so we had it done by a differant machine shop and it ran great so we ate the rebore and learned anouther lesson.
Sorry for being so long winded--Bob

 

[OperativeK]

Re: Motor floods at idle when trimmed all the way down

You might want to take the flywheel off and check the that there is no sheering on the key. If there is turn it the opposite direction and then put the flywheel back on. Its worth a look. ; )

might check your fuel pump diaghram too.

 

[imported_bucketmouth]

Re: Motor floods at idle when trimmed all the way down

Thanks for the input OpK. I am a Texan living in Tennessee. I will look into the flywheel and the key.

To answer Lads questions:
1. The motor was originally taken in because the #3 Cylinder was down and the motor would not fire a lick. This info comes from my brother in law who previously owned the boat.( Had I taken it to the shop he recommended I probably wouldn't need any help,but hindsight is 20 - 20)
2.On the boring to 040 I asked on pickup what I needed to do as far as running speed, rpm's, length of running and what grade of fuel. The answers were half throttle, under 4000 rpm's run it to the motor reaches operating temp and shut off to let cool down and run again. And middle grade fuel 89 octane, nothing about adding more oil during break in or first full tank and nothing about the pistons. I had no idea that they pistons used were wiseco and that they required a special break in. I have run the motor twice, and the first time I never got over 4000 rpm;s and only ran it for five minutes and retrailered because of fog rolling in off the river. The second time is when she went dead in the water and I was pulled back to the dock by my fishing partner.
As far as mismatched blocks I again have no idea, My brother in law ran the boat for 5 years before he let it sit for two years while he ran his Bullet around the river. Of course the motor had gone down first before he let it sit.
The shop who took my money never mentioned anything about a mismatched block before it was sent to the machine shop for re- boring. It was only until the timing or lack of idle would never get right for them that the mis- matched block BullS--t came to light.