Mercruiser 140hp running rough

[Greichert1]

Hey everyone, I'm back with a few more questions that I'm hoping someone can answer for me. I have a '72 mercruiser 181 (140hp) with a m&w turbo on it. I purchased the boat not running and have been through hell getting it to this point. She now runs but not very well. So far I've replaced the intake/exhaust manifold due to an internal crack causing milky oil. New gaskets from the head up. Ignition system is all new and just rebuilt the carb. She starts right up and runs ok but pretty shaky while holding any rpm's other than idle. And if left at idle for more than a minute or so, it seems to load up with fuel and completely bog when you get back on the throttle. Also smells very rich while running. It seems to me that It could be a timing issue. Does anyone know if the turbo changes where I should have my timing set at? I'm very mechanically inclined but don't know much about turbos. Thanks in advance for any advice!

 

[Levinz11]

Re: Mercruiser 140hp running rough

Do you have pics of the set up?

 

[tinkerguy70]

Re: Mercruiser 140hp running rough

The rich mixture is probably in the carb, most likely the power valve is stuck open if it is loading up all the time.
Might be time for a carb rebuild. I can't imagine ignition timing causing the problems you're describing.

 

[Greichert1]

Re: Mercruiser 140hp running rough

 

[Greichert1]

Re: Mercruiser 140hp running rough

Thanks for the quick responses! Let me just say that I would have never even gotten this far if it wasn't for this forum and all the helpful advice. Thanks everyone! Posted a basic picture of the turbo setup Levinz. let me know if anything doesn't look right because im not really sure that this setup has ever run properly with the turbo installed. Like I said, it wasn't running when i bought it and the previous owner had minimal info for me. And tinkerguy, the carb was my first thought also, so I rebuilt it and just got it back in the boat last weekend. Runs slightly better than before the rebuild, but no major difference. And the power valve was in good shape, moving freely and got a nice soak in berrymans chem dip just incase. I just tried to adjust the timing by ear and it seems to be running significantly better when above idle but still not perfect and now im getting a major hesitation when leaving idle. I am at a loss here guys. Any ideas or info would be much appreciated.

 

[tinkerguy70]

Re: Mercruiser 140hp running rough

If you're sure it's not the carb, then I'm at a loss. Hope you get it figured out.

 

[Greichert1]

Re: Mercruiser 140hp running rough

If you're sure it's not the carb, then I'm at a loss. Hope you get it figured out.

Thanks, I hope I figure it out to. As for the carb, it seems to be working properly as far as i can tell. Im no expert but the old rochester 2brl's dont seem to have much in the way of adjustment. I'll keep at the research and as always, thanks for the input.

 

[Levinz11]

Re: Mercruiser 140hp running rough

View attachment 183359

That's pretty interesting. I always thought the force induced air would be going down the throat of the carb?

 

[Bondo]

Re: Mercruiser 140hp running rough

That's pretty interesting. I always thought the force induced air would be going down the throat of the carb?

Ayuh,... That 1 draws through the carb,... less complicated than a blow through set-up...

Even though the carb was rebuilt, it Sounds like it's still the Problem...

 

[Greichert1]

Re: Mercruiser 140hp running rough

Ok, definitely appreciate the advice guys. I'll keep looking into the carb and see what I can figure out. And ideas on what it could be specifically since I just rebuilt the carb? Could the power valve be bad even though it moves freely and seems to seat properly? For the cost of a rebuilt rochester it may be worth it to just change the entire carb... Thanks again for the input and ill keep everyone posted on any changes.

 

[TurboM700]

Re: Mercruiser 140hp running rough

Carbs the problem but keep in mind that suck thru turbo carbs dont like to idle for long periods of time and if there is any leaks in the intake side they will go lean and misfire which can seem like it goes rich.

Check fuel pressure float height and make sure the float actually floats and doesnt have gas in it.

Also something you can try when it seems like it load up is spary carb/strating flood in the carb and see if it dies right away or starts to run better this will tell you if your lean or rich.

Also when its loading up if you have rubber fuel line try pinching it off and see if it starts to run better( it will die eventually) but this will help narrow it down to the carb.

Also sent you a PM as I very interested in this set up for my I/O pontoon.

Mike

 

[Greichert1]

Re: Mercruiser 140hp running rough

Thanks for the advice Mike. Definitely appreciated. I'll search for any leaks on the intake side with some propane or carb cleaner. I have no idea on the fuel pressure but I will check it out. The float height and drop are correct and it definitely floats and has no liquid in it. The starter spray or pinching the fuel line when it's loading up is a great idea. I will also check that out and get back to you. And I would be glad to assist with and info you might need, but I didn't receive any PM's. Maybe try again and thanks again for the advice.

 

[TurboM700]

Re: Mercruiser 140hp running rough

Your welcome let me know what you find out.

Not sure why the PM didnt go thru but I will ask the questions here as I'm sure others have the same questions

I was wondering if you could get me some close up pictures of the Intake and Exhuast routing along with pictures of the turbo and any numbers on it.

Last yr I built this http://forums.iboats.com/completed-boat-projects/pontoon-conversion-inboard-outboard-573089.html with a 3.0l Mercruiser in it and I have always wanted to add a turbo to it and call it "turbo toon" looks like that could happen with out doing another motor swap.

 

[Bondo]

Re: Mercruiser 140hp running rough

Your welcome let me know what you find out.

Not sure why the PM didnt go thru but I will ask the questions here as I'm sure others have the same questions

I was wondering if you could get me some close up pictures of the Intake and Exhuast routing along with pictures of the turbo and any numbers on it.

Last yr I built this http://forums.iboats.com/completed-boat-projects/pontoon-conversion-inboard-outboard-573089.html with a 3.0l Mercruiser in it and I have always wanted to add a turbo to it and call it "turbo toon" looks like that could happen with out doing another motor swap.

Ayuh,... The picture posted above shows it quite well,...

The turbo bolts onto where the riser used to be,...('n it appears the gaskets are Leakin')
The intake draws through the carb, 'n blows through the black castin', which is bolted onto the intake, where the carb used to be...
The OEM was M&W Machine I believe...

 

[Greichert1]

Re: Mercruiser 140hp running rough

Yup, bond-o's explanation is accurate. I would be happy to get you some better pictures, part numbers and a more detailed explanation as soon as I get off work today. And yes, it is M&W but I don't think it's oem equipment. I believe the turbo setup was originally off of farm equipment. From what I understand, it was fairly popular to retrofit these turbos onto these little mercruiser 2.5 and 3.0's. I would assume the parts are reasonably easy to find. Quick question though bond-o. You say it appears my manifold gasket may be leaking... Do you actually see evidence of that in the picture or you believe they are leaking based on the symptoms? Because basically every gasket on that engine is brand new although that's not to say that one of them didn't get pinched upon install... As always, thanks for all the input everyone. I will do some more testing and tinkering after work today and keep you all posted.

 

[TurboM700]

Re: Mercruiser 140hp running rough

Bond-o I fully understand how the turbo system works. This isnt my first rodeo when it comes to carb or efi and turbos. Have built plenty of 400hp turbo snowmobiles.

The reason I was asking for pictures is to try and get a feel for what size turbo it is. I have more research in the last few hrs about turbo boats then I probably should. It seems like if I want to keep the turbo under the dog house I will need a water cooled exhaust housing or build one. To keep temps down.

A highly modified 1.8t VW will use a Garrett 2871 were my 1000cc turbo 2 stroke snowmobile will use a 3071 or even a 3271 if I wanted for only race trim.

I could see on a boat you would want somewhat of a smaller turbo that would spool quick and lower rpm so it doesnt just blow the prop loose.

Sorry for the derail OP just thought it was a cool idea.

One other thing I thought of to check for Vaccuum leakes in brake cleaner when it running spary it around all the air intake,turbo,manifold gaskets etc and see if idle changes.

Also wouldn't hurt to give her a compression check make sure its a health engine.

Another good idea which should be easy to do is make a simple block off for the exhaust and carb and pressures the system to 10-15psi and see if it will hold pressure.

I do this on all the turbo kits wether there 2-4 stroke and I usally like to see them hold pressure in the 10psi range for about 30mins.

Just somemore ideas to help narrow it down.

Thanks again and I look forward to the pictures.
Mike

 

[Greichert1]

Re: Mercruiser 140hp running rough

No worries about getting off topic Mike. I'm more than happy to help with any info that i can provide. Everyone on this forum has been so helpful and informative that it would be rude of me to not return the favor. I'm off work at 5pm pacific time and will definitely get you some pics and part numbers asap. As for the temperature issue, I have also heard that these setups have problems when stuffed under an engine cover although the M&W setup that I have is a water cooled intake, exhaust and turbo so I couldn't see temp being a big issue but in addition to the water cooling, I also cut a nice little air scoop out of the doghouse, just above the carb and turbo, just for good measure. Compression is good by the way. It's been a while since I checked but I think all cylinders were right around 120psi. I will try to search for intake leaks with propane or carb spray when I get home and a block off and pressure test is a great idea if I can't find anything. Thanks again for all the input and ill keep everyone posted.

 

[Bondo]

Re: Mercruiser 140hp running rough

And yes, it is M&W but I don't think it's oem equipment. I believe the turbo setup was originally off of farm equipment. From what I understand, it was fairly popular to retrofit these turbos onto these little mercruiser 2.5 and 3.0's. I would assume the parts are reasonably easy to find.

Quick question though bond-o. You say it appears my manifold gasket may be leaking... Do you actually see evidence of that in the picture

Ayuh,... Sorry I wasn't clear,... M&W is the Oem of the turbo kit, not the Whole motor...
They had those Kits back in the 70s,...
They're quite rare now-a-days, so I donno's yer gonna find many of 'em,...
Yer's is only the 2nd, or 3rd I've seen...
'n No, it wasn't for a tractor, it wouldn't be water cooled if it was, it was For yer motor...

I see Rust stains on the turbo, hence my thought it's Leakin'...

 

[Bondo]

Re: Mercruiser 140hp running rough

Bond-o I fully understand how the turbo system works. This isnt my first rodeo when it comes to carb or efi and turbos. Have built plenty of 400hp turbo snowmobiles.

Mike

Ayuh,... I didn't say it Is yer 1st rodeo,... Yer chosen name told Me, it Weren't...

'n, Yes, ya Need a water cooled housin' if it's an enclosed motor....

If it was an Open motor, like many ole Jet Boats, you could run a regular housin', 'n yes, it'll be glowin' Red hot...

Btw,... I see the Id tag, On the turbo in the picture....

 

[Greichert1]

Re: Mercruiser 140hp running rough

I dunno bond-o, It says farm power equipment right on it... Not that that's really the point. And the rust is recent, due to rain water from when the cover blew off a couple weeks ago. I will definitely do some serious checking for leaks though just incase. Mike, sorry about the pictures and part numbers. I ended up working late and it was dark when I got off. I will get them to you first thing tomorrow though. As for the availability of the parts, I have no idea but ill get you those part numbers so you can check it out. As a matter of fact with the way this thing has been fighting me, I just may have a turbo setup for sale soon. I plan on finally actually putting some time in on the old girl tomorrow so I'll put all that good advice to use and let you all know how it goes. Thanks again for all the input