yamaha 3.0 l4 blew head gasket help!

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Flashcardsgo

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Ive got a 1993 Harris Flotebote with this engine sterndrive combo and i have redone most of the boat with new, floors,carpet,seats etc so i don't want to dump it or trash it . i have had the lower unit rebuilt and has new bellows also. pulling a tube with grandkids must have been too much for my old girl and it started ticking and missing and smoking . i pulled the valve cover and i have water in the oil up top . The dip stick oil wasn't milky or even thin so i think i blew head gasket . i cant find new parts or many used parts but would like to know if i can use a automotive engine cyl head from a gm 181 ci 4 cyl chevy and also if i can can i put a mercruiser exhaust manifold on it . i had a leak on the manifold before and we bought a mercruiser one that would bolt up but the exhaust ports were not the same . if i replace head with one that matches the mercruiser ports is this possible or can someone tell me what my options are because i want to fix the engine for sure thanks and sorry for the book . thanks Tom
 
Bondo

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if i can use a automotive engine cyl head from a gm 181 ci 4 cyl chevy and also if i can can i put a mercruiser exhaust manifold on it . i had a leak on the manifold before and we bought a mercruiser one that would bolt up but the exhaust ports were not the same . if i replace head with one that matches the mercruiser ports is this possible
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Ayuh,..... Welcome Aboard,...... Chevy has never used that motor in a car, nor a truck,.....
You can use Mercuuiser parts for yer motor though,....
It don't matter if the exhaust ports are the big ones or the little ones, the manifold will still work,....
Marrying it to yer Yamaha outdrive exhaust port is what's necessary,....
As for gaskets, 'n internal motor parts, Merc or Volvo pars will work,....
 
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thanks for reply the ports on the head that mercruiser offers reman heads there are 8 ports and on my yam there are only 6 . i remember the manifold we bought 1/2 of the port would have been blocked if we bolted it to the head .wouldnt that cause flow issues , loss of power or cooling something like that. im just trying to figure out what i can do to get the motor back running before next season without spending a fortune . i tried to attatch a picture of the diagram fromcrowley marine but it wouldnt let me
 
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Bondo sorry to go on lol but there is a local boat guy I've known for 40 years that has a few 3.0 inline 4 cyl motors i think 1 is a Volvo and one is a mercruiser , he has 5 or 6 manifolds but the ports are different than my head . your saying that doesn't matter so could i bolt one of the heads from his motors to my block and use either a mercruisr manifold or even try to resurface my manifold and use that to keep from having the elbow assembly issues . if not willl one of those manifolds have a elbow assembly i can use my rubber boots and clamps etc with and do you know where i can source the new gaskets for the yam if i reuse it
 
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now im really confused because another post where a guy wanted to swap yam parts for mercruiser they said he needed to swap all the wiring ,lower unit ,and much more . im just wanting to basically do a head gasket job or head swap to get my boat running again . i want to use my block and all my exhaust parts im ok with swapping head and manifold to mercruiser if it will work but you said marrying the mercruiser manifold to my yam exhaust might be big issue
 
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airshot

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Why not get the head resurfaced ? A few years back my 3.0 Merc had a head gasket go bad. Mechanic told me that was common if the engine ever overheated. Pulled the head, took it to local engine shop, they resurfaced the head, reground all the valves and reseated them, along with new valve springs. A little over 300 bucks total for the shop. Block deck was flat and no scores in the cylinders. Put everything back together in an afternoon and ended up with compression 147-150 across all four cylinders and she ran like new ! Pull it apart and see what you really need, if cylinders are good, you might just need the head reworked, far better to rework than gamble on a used one !!
 
Scott Danforth

Scott Danforth

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Get a complete Volvo or Mercruiser 3.0 long tail and swap out to replace all the Yamaha stuff that is no longer supported
 
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Flashcardsgo

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Bondo said:
Ayuh,..... Welcome Aboard,...... Chevy has never used that motor in a car, nor a truck,.....
You can use Mercuuiser parts for yer motor though,....
It don't matter if the exhaust ports are the big ones or the little ones, the manifold will still work,....
Marrying it to yer Yamaha outdrive exhaust port is what's necessary,....
As for gaskets, 'n internal motor parts, Merc or Volvo pars will work,....
Click to expand...
Will parts for GM from Auto Zone work like they did in my 3.0 6 cyl 165 hp motor on my runabout. They looked up a 250 inline 6 truck motor for the lifters & the pushrods Thanks
 
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I have some updated information. My retired boat mechanic that worked on this boat several times told me after I sent a video of it running that I may not have a blown head gasket. I made a video and because some mechanic friends think it might be bottom end noise I checked with a few more of my sources not a unanimous consensus. The boat mechanic told me he thought sounded like lifter out of adjustment more than a rod ! Praying he’s right even though I already found and bought a near perfect head , manifold from the same motor which is a small miracle to find, I told him that the valve cover and top of head had milk on them but the dipstick didn’t and he said those engines vent really hard and might not be a blown head gasket ! I really hope he’s right but I’d like to know you guys opinion also. Tried to send pics but won’t let me. Thanks again. Tom
 
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airshot said:
AND....be sure to run a tap into those holes to clean the threads or you could get a false torque reading.
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Thanks for the advice. After some new information and a compression test I’m hoping I may not need to replace head gasket and it’d just a lifter or rocker arm issue
 
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airshot said:
Why not get the head resurfaced ? A few years back my 3.0 Merc had a head gasket go bad. Mechanic told me that was common if the engine ever overheated. Pulled the head, took it to local engine shop, they resurfaced the head, reground all the valves and reseated them, along with new valve springs. A little over 300 bucks total for the shop. Block deck was flat and no scores in the cylinders. Put everything back together in an afternoon and ended up with compression 147-150 across all four cylinders and she ran like new ! Pull it apart and see what you really need, if cylinders are good, you might just need the head reworked, far better to rework than gamble on a used one !!
Click to expand...
I bought a head that’s in great shape and a new manifold and xtra lower unit while they were available because they are virtually impossible to find. But a retired boat mechanic that used to work on the boat told me that the video I sent him noise that several people thinks is bottom end that he thinks I may have a rocker arm too tight , valve out of adjustment or dead lifter instead . The milk on the head and valve cover but not in the oil may be from that and he said those motors vent very hard. I think I’ll adjust the valve train before I pull the head would be much less work I plan on replacing the lifters , pushrods and the manifold regardless. My compression readings were 180 across all 4 cyl
 
Scott Danforth

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Flashcardsgo said:
Will parts for GM from Auto Zone work like they did in my 3.0 6 cyl 165 hp motor on my runabout. They looked up a 250 inline 6 truck motor for the lifters & the pushrods Thanks
Click to expand...
The GM 3.0 4 cylinder was NEVER used in an automotive application.

It's a GM industrial motor used in forklifts, gensets and trash pumps. It was also used in boats
 
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airshot

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Flashcardsgo said:
I bought a head that’s in great shape and a new manifold and xtra lower unit while they were available because they are virtually impossible to find. But a retired boat mechanic that used to work on the boat told me that the video I sent him noise that several people thinks is bottom end that he thinks I may have a rocker arm too tight , valve out of adjustment or dead lifter instead . The milk on the head and valve cover but not in the oil may be from that and he said those motors vent very hard. I think I’ll adjust the valve train before I pull the head would be much less work I plan on replacing the lifters , pushrods and the manifold regardless. My compression readings were 180 across all 4 cyl
Click to expand...
Re check your compression numbers, new engines are only 150 psi, might be a bad gage.
 
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kd4pbs

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Having suffered in the past being an owner of a Yamaha Stern Drive, they are used to exist a company who made fiberglass adapter elbows to mate MerCruiser exhaust systems to the Yamaha Drive. I had two of them on the Chevrolet 350 on my drive. The boat was very nice when I sold it, but I was very happy to get rid of it solely due to it having that outdrive. That was over 10 years ago and I can only imagine attempting to get parts for them nowadays would be exponentially more difficult.
 
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Mc Tool

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If the engine was over cooling you may get milk in the rocker covers simply because the oil doesnt get hot enough to boil out any moisture out and it condenses under the covers and thus the milk . Is your t/stat working ?
 
matt167

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The engine itself was used by OMC, Volvo and a Mercruiser along with many other manufacturers for things like water pumps and fork lifts. So there is no shortage of parts for them.. where your going to have issue is with anything that is Yamaha specific. You’ll need to get an exhaust riser to fit the exhaust on your boat. It shouldn’t be impossible but you’ll have to figure out what fits.
 
Grub54891

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I get a bit of milky in mine, mostly when not running it hard enough on my 350 acre lake. If I take it out on lake Superior I can get her going wide open for a good half hour or more and cruise all day. The milky clears up well. On the smaller lake I do run it wide open on occasion but it gets boring quick running circles.
You more than likely do have other issues with the valve train.
 
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