Mercruiser 140 Rebuild

[9533Zero]

HURRAY!! I get to rebuild a motor! Actually, I'm looking forward to the project.

I've posted the story of my "new" boat under "How to rotate mercruiser 3.0 manually" and am now to the stage where I'm doing the engine work. Haven't stripped the block down yet but I'm working on the head, carb and manifold.

I will chronicle my progress here and so for the first question... The head is not that bad, although it had water in the intakes. I will strip it and have it reconditioned, but plan on replacing the valves myself. I started to look at the springs and realized something was wrong. It looks like only the rear 2 valves, cylinder 4, have the inner damper valve springs. The other 6 have only the outer springs. This tells me that A - I don't know as much about motors as I thought, or B - this head has been "rebuilt" before. So far I see no evidence the block has been touched so I'm checking with the experts. Is this correct or am I missing something, like parts? There is no mention of this condition in the manual. Thanks!

Steve

 

[Don S]

Re: Mercruiser 140 Rebuild

but plan on replacing the valves myself.

You have a valve grinder? I have never seen a new valve ready to install into a head. I always true them up on a valve grinding machine,(and they are always a little off). Then, regromd the seats and lap the valve in. You also need to check the valve guides and knurle them if there is too much play.

 

[fishrdan]

Re: Mercruiser 140 Rebuild

Rebuild or re-ring?

I agree with Dons, the machine shop should be doing all the head work. I rebuilt my 3.0 last spring and the head work was about $150.

If only 2 of your springs have dampners I would say someone was in there before. If memory serves me right, all of the springs should have dampners.

 

[Don S]

Re: Mercruiser 140 Rebuild

HURRAY!! I get to rebuild a motor! Actually, I'm looking forward to the project.

Have you ever rebuilt a motor before? From the sounds of things, this might be your first one, no manual, and hoping to just buy some parts and put them in and all will be wonderful. Unfortunatelly, there is a lot more to a rebuild than just throwing a few parts at it.
Before you order that first part, you need to inspect everything "By The Book" to make sure it's usable.

Do you own the Mercruiser OEM service manual? Not a Seloc or Clymers, or your engine will never work.
If not, download it now at the link below.
http://www-alt.mercurymarine.com/mnetdata/SERVICE/CRUISER/Servmanl/10/cover.pdf

It's about 150 MB in size, so give it time to load. Best bet is to right click the above link and save it to your desktop so you can find it.

It would also be really handy if you put your engine Merc SN or even a year in your signature or something so we have some idea of what you are working on. They are NOT all the same.

 

[chiefalen]

Re: Mercruiser 140 Rebuild

It ain't cheap ether, you'll need a master rebuild kit.

You should have a the head done by a pro.

You have a motor stand or borrow one, i call it a rotisserie.

How are the mating surfaces between the head and block?

Did you inspect for cracks, holes pulled out.

You will need the manual for proper torque values.

And a good torque wrench, don't think you can do it without one.

Crank, hows it look, new one maybe, i think 200 bucks for that.

Just let us know if you need any help.

Maybe someone has laying around a part or two you can use, just ask.

 

[alumi numb]

Re: Mercruiser 140 Rebuild

have built a few engines in the past and no way would i do the head myself.
should magnaflux it for cracks, you don't know if it's warped on and on.
the block deck should be checked and the block may have to be line honed or bored.
rods magafluxed and resizes and are the block bores ovalated, again on and on.
then there's the crank.
sounds like you need a machine shop to help.
then again mabe i'm reading to much in, hope so.
wish you the best.

 

[dan t.]

Re: Mercruiser 140 Rebuild

having rebuilt my share of engines over the years I would never advise anyone to knurl valve guides. this is a temporary fix at best. if a guide is worn enough to warrant knurling it needs to be replaced. sorry to contradict you Don but I have had a few come back to bite me.

 

[9533Zero]

Re: Mercruiser 140 Rebuild

Its been a while since I last posted on this thread, but I took the good advice offered and had the head reworked by a GREAT independant machine shop in Ft. Walton, FL, F&S Machine. They are also checking my manifold and riser.

I'm rebuilding the carb. Its a Merc Carb and I have a question. On the underside of the air horn body there is a post pressed into the air horn body with a spring on it. This spring is rusted and has broken. I'd like to replace it but the post appears to be pressed in and I see no way to change it. Nothing mentioned about this part in the manual, although it is shown in the pictures. What function does this spring serve and is it critical? Thanks!

Steve

 

[9533Zero]

Re: Mercruiser 140 Rebuild

One more question, anyone know a good source for new rods and lifters for this motor? Thanks!

Steve

 

[chiefalen]

Re: Mercruiser 140 Rebuild

This site doesn't carry them ?

If i were you i would call this site, they will work with you and you will get the right price also.

 

[wht89gt]

Re: Mercruiser 140 Rebuild

Steve how much did they charge you for machining i live in destin and have a busted 3.0 im rebuilding