2000 40hp mercury; No compression in top cylinder under load.

[Chris Cole]

Re: 2000 40hp mercury; No compression in top cylinder under load.

I am in the process of tearing the motor down completely . When I have the block taken apart I will post some more pics. I hope I don't need a new block.

 

[Chris Cole]

Re: 2000 40hp mercury; No compression in top cylinder under load.

Hello Forum,

The saga continues; I tore my motor almost completely down. I have taken a look at the crankshaft assembly, my piston looks okay except for a few frags of metal from the piston sleeve. My cylinder wall next to where the spark plug is has a couple of frags of metal wedged in it from the piston mashing.
It looks like the sleeve has actually slid down into the combustion chamber, and the rod bolts rubbed the sleeve causing the break. I am posting pics of everything I have described.

The first three pictures show the piston sleeves in two cylinders. It is obvious the top cylinder's sleeve has slid down. Are all of the carbon deposits in these pics normal?

The second set of pictures is the connecting rod bolts. Notice how they have been rubbing. The weird thing about this set is that there are abrasions on the bolts on all three rods?????

 

[Chris Cole]

Re: 2000 40hp mercury; No compression in top cylinder under load.

There is a 5 file max upload, so I will continue in this reply.

In this set of pictures notice the metal frags in the piston. Is all of this black normal, or is it a sign of detonation?

Okay,
What do I need to do next guys?

 

[Chris Cole]

Re: 2000 40hp mercury; No compression in top cylinder under load.

Good morning forum,

Bump...Bump

 

[achris]

Re: 2000 40hp mercury; No compression in top cylinder under load.

Hi Chris,

So, what have we got here?

1. Carbon deposits are normal, it's a 2 stroke. However, yours are really dry, indicated an overheat, but we already knew that! When I was tearing down engines on a regular basis I could tell the brand of oil from the amount and type of deposits. The cleanest oil was Quicksilver, and the dirtiest was Valvoline, followed closely by Shell and BP. The deposits are normally 'wetter, oilier'.

2. That is definitely a slipped liner, again because of the overheat, which must have been quite severe to heat the alunimium up that much .

Recommendations....

1. Lightly clean up the piston with the damage with a fine file. Don't take too much metal off.

2. The overheat will have softened the rings on all pistons, replace all rings. Also check for damage on the piston skirts. Make sure they haven't 'grabbed' anywhere.

3. That block is a bin liner. The only way to have a reliable engine is to get a new block. Remember that a new block includes the crankcase cover, they are machined together as a matched pair. I have seen engines that were rebuilt with a non-matched cover and it a disaster in the making.

Other than that, well done on getting this far.... Keep up the good work.

Chris...............

 

[Chris Cole]

Re: 2000 40hp mercury; No compression in top cylinder under load.

achris,

You don't think I could have a machine shop resleeve that cylinder, or heat it up and press that sleeve back into place? WillybWright suggested heating the block and pressing sleeve back, he also said it might not be reliable though.

I believe a new block will cost about $1300 per mercruiserparts.com.

 

[achris]

Re: 2000 40hp mercury; No compression in top cylinder under load.

Chris,

I guess the short answer is: yes.

The long answer is how far out do you usually go? Can you row back in or do you carry an auxillary? How much damage will it do when the liner slips again, and trust me, it is a question 'when' and not 'if'.

If you do decide the repair path, make sure you use a machine shop who is very familiar with working with 2-strokes. Many shops that work on 4-strokes don't understand the vaguaries of 2-stroke engines....

Chris..............

 

[Chris Cole]

Re: 2000 40hp mercury; No compression in top cylinder under load.

Okay,

Next logical conclusion for me is to get a block, I guess. A sleeve is slipped on my current block and my spark plug threads are stripped on the top cylinder.

Question:

Can someone give some information on where to get a new or used cheap block? Mercruiser is telling me 1300 bones, that's too much!!

Please help.

Mercury 2000 3cylinder 40horsepower
Serial # OT096183

 

[redjmp]

Re: 2000 40hp mercury; No compression in top cylinder under load.

Well I gotta ask if you this motor always ran this way for you or did it work fine before?
Since it is the top sleeve that has slipped, it is most likely due to an overheat at the top of the block. Could be due to a slipping impellor so I ask did you change it out yet? I'm not so sure about your model but if it has a head gasket that lets some gas escape into the cooling passage, then that would drive the coolant level down leaving the top of the block without any coolant and causing an overheat as well.
Otherwise as long as these possible instances don't occur again, there should be no reason for the sleeve to slip again. The spark plug hole can be easily fixed with a helicoil so that wouldn't be a reason to scrap the block.
I think a good shop might be able to repair your block to prevent that liner from slipping again. Possibly knurling the outside of the sleeve or even pinning the sleeve in somehow. Maybe that sleeve is a little out of spec and a proper size replacement could be obtained? You can try mongoose machine shop in pt.coquitlam bc canada and see what they say. They only do 2 stroke stuff and are highly recommended.

 

[Chris Cole]

Re: 2000 40hp mercury; No compression in top cylinder under load.

redjmp,

Thank you for the response. To answer your question about how the motor was running before; the answer is the motor was running just fine before I ran it hot. As I took the induction manifold I looked at the gaskets they were just fine. Where the crankcase cover separate's from the block there is not a gasket, just some kind of lock-tite or something. All other gaskets looked fine.
I brought the crankshaft assembly as well as the block to an outboard mechanic who said he could fix it no problem. He found some additional damage that I didn't though.
Middle cylinder sleeve is scuffed real bad.
Middle piston skirt is shot.

He said that he could resleeve the two cylinders, replace the pistons and rings, as well as place a insert for the stripped threads.

I told him I didn't want to break the bank on this thing, but he assured me he could get some pistons that were cheaper than mercs price, 177/piston.

He is going to call me today with an estimate, I hope it is not that pricey.

 

[Chris Cole]

Re: 2000 40hp mercury; No compression in top cylinder under load.

Just got the quote for 3 new pistons, rings, 2 resleeved cylinders, and an insert for the stripped spark threads, and a cleaned block. $ 660 Bones.

I don't think it is to bad of a price, so I have went ahead and taken the offer.

Am I going to need to do anything special when running new pistons and rings??? Help, please.

 

[redjmp]

Re: 2000 40hp mercury; No compression in top cylinder under load.

Geez those are pricey pistons at 177 but ok if it includes the sleeve and rings.
Try boats.net. They have the cheapest prices I have found.

 

[Chris Cole]

Re: 2000 40hp mercury; No compression in top cylinder under load.

Hello Forum,

New question and thought on the rebuild of my mercury motor.

Before I got this mercury 40hp it was converted to a 60 hp motor; so said.
The only things that I can tell that are different from a 40 hp on this motor are the Carbs, and the reed assembly.


I got to looking at some of the spec changes from 40 to 60hp, and see that a 40 hp motor is supposed to get from 5-7 psi water pressure under WOT. A 60 hp is supposed to get in between 7-12 psi water pressure under WOT.

Question:
Do you guys think that my motor will still draw 5-7 psi at WOT, or 7-12 psi?

What determines how much pressure that your motor will draw at WOT?

Would running a 60 hp motor at 6 psi water pressure cause an overheat, or just cause the engine to run a little hot?

 

[Chris Cole]

Re: 2000 40hp mercury; No compression in top cylinder under load.

Hello mercury forum,

I ran my newly rebuilt mercury today and it ran like a mad cat!!!! Yes.....!!!! I had the pistons and rings replaced, two cylinders resleeved, and a spark plug insert. The mechanic put the pistons in the block and attached them to the crankshaft. I tore the thing down and rebuilt it myself. Thank you to this forum for being insightful and helping me along in diagnosing the problem with my motor. I am a newbie and this forum was crucial in my understanding of my motor. I know my motor inside out now.

For every one that responded thank you. much appreciated.

 

[The-Machinist]

Re: 2000 40hp mercury; No compression in top cylinder under load.

I would invest in some type of temp sensor or guage to mount to the top of your block, cheap insurance

 

[Chris Cole]

Re: 2000 40hp mercury; No compression in top cylinder under load.

Masterofmachines,

The machinist that resleeved my cylinders relocated my tell tale to the top cylinder, this gives me a better indication of how hot that cylinder is running. My overheat sensor works as well. Thanks for the advice.