spring maint planning for old 150 Yamahas

[fastkenny]

there is still 1' of snow on the ground, but i'm getting the itch to take the cover off the boat...<br /><br />I have twin '88 150 carb'd motors and I'm planning this spring's maint and shopping for parts. I've had this boat for 1 yr, it ran beautifully last season and it was professionally maintained before that. I'd like to save some $ by doing this myself and learn a little about the machines. I have the Clymer manual but it seems lacking in places.<br />I was planning on doing the following. I have searched this forum and found lots of great info. I still have a few questions that I couldn't find answers to. Am I missing anything? What do you all do that is different? Thanks for your feedback!<br /><br />Cooling system<br />-Replace water pumps (lower unit fluid change was done in the fall, will it need to be redone when lower is dropped?) I think the water pumps were last replaced 2 or 3 years ago, so lower unit should come off ok. There are burn marks where the heat wrench was used last time. I know this task can be tricky, are there any good hints or tricks? I've found some of rodbolts posts on this subject for newer models, I assume they apply for the older ones as well? <br />-Tstats and poppit valves (check, clean or replace)<br />-Is there a good way to clean/flush cooling passages without pulling heads etc? Can mineral deposits be dissolved with some kind of solvent?<br />-Maybe install a water pressure guage or temp guage, is one preferable to the other? anyone have both?<br />Fuel Sys<br />-replace Racor elements<br />-is there a way to check fuel pumps? or should they just be replaced every few years? what about just replacing the diaphram(s)?<br />-what should be done with the carbs?<br /><br />Oil Injection<br />-pull and clean remote tank pumps and filters<br />-what should be done on main (engine mounted) tank?<br />-check warning light/alarm circuits<br /><br />I plan to do a compression test, last year all 16 cyl were 110 +/- 5. I'd like to do a leak down test also - how is that done? What special tools would I need?<br /><br />Is it a good idea to de-carb at this time? Maybe it's best to do it before I put new plugs in? Is it worth doing if there is no apparant problem?<br /><br />In general, after many hours reading this site, it seems most catastrophic engine failures are related to overheating, oil starvation, or lean condition. I'd like to get ahead of anything that would cause one of these problems later. I'd like to get a few more years out of these motors.<br />THANKS for any feedback!

 

[rodbolt]

Re: spring maint planning for old 150 Yamahas

wow a long list<br /> no you wont have to rechange your oil. aretheses 20" or 25" motors. yes change the poppet valve grommet, the valve is normally ok. yes clean the remote oil tanks and replace the remote oil filters. you will see them inline on the bottom of the tanks. its rare that the remote tanks get cleaned and if you dont use nasty funnels they rarely need it but the filters will clog.. if you remove the oil sensor and screen assy from the enigine tank make SURE you retrive the little foam rubber seal. Idrain the tank by carefully removing the vynil water trap. sometimes a bit of heat makes them pliable again. dont snapthe nipple off the tank. when reassembling the sensor to the screen pay attention to the flat on the rubber and the vent hole near the top of the screen and use a NEW foam rubber seal.in my opinion temp gauges and pressure gauges are teats on a boar hog. especially if you try to pull the block plus if they have been in since 88. usually the threads come out with it. I reccomend replacing the pumps every 3 years. they are rebuildable but the parts are almost as much as a pump. that boat wasnt U-bet IV was it .look at the service maint guide. on saltwater motors of that age I get nervous pulling heads unless I have to.

 

[fastkenny]

Re: spring maint planning for old 150 Yamahas

Thanks rodbolt!<br /><br />No, not U-bet. This is an '88 Grady White Gulfstream. Both the power heads have been taken off in the past few years to do the shift rods, so I think they'd come off fine. Hopefully I won't have any reason to do that! I guess I'll save the $ and forget about the guages, I thought is was a good way to see a problem develop early.<br /><br />I will do a thorough cleaning of the remote tanks, they've been in there since '88 and I don't think they've ever been serviced. You need to pull the deck panel out to access them, i'll be installing a hatch.<br /><br />Maybe I'll replace 2 pumps on 1 motor this year, do the other next year to spread out the cost. Is there anything that should be done to the carb? I fogged them good in the fall, fuel was stabilized. Do I need to drain the carbs, or just fire them up? What about de-carbing? Is it worth the hassle?<br /><br />Thanks for the tips!

 

[rodbolt]

Re: spring maint planning for old 150 Yamahas

you may spread the cost of an overhaul. oil pumps,fuel pumps and water pumps degrade. they dont have to quit. the block mounted oil pumpis usually trouble free. without looking at it I cant tellyou if its been updated. the fuel pumps wear out in a few years and no longer supply fuel for WOT causing lean outs. the diaphrams also rupture allowing raw gas into the crankcase wich can lead to crank,bearing and piston failures from a lean oil condition. the water pumps,t-stats and pressure control valves/grommets need to be serviced at least every other year. the manual says to inspect yearly or every 200 hours. the biggest failure of the oil transfer pumps is debris and connector corrosion. connector corrosion can also create a oin control module failure. my advice is if you cant financially maintain two engines is to sell it and buy something with a single. the power heads being off have nothing to do with whether or not the cylinder heads will come off without breaking a lot of fasteners. twins are 3 times the maint cost of a single. seems with twins someting is always in the way. a lot of the older grady's with below deck tanks have a large screwed down panalthat can be removed for access. some of them require fish box removal to acess the tanks. which is why most never see maint until something breaks and the seatow bill arrives. if stored correctly the carbs should be ok. a good decarb then a set of plugs and if the motors wont turn up it may be time for a carb job as well.what part of the world is this grady run in ?

 

[fastkenny]

Re: spring maint planning for old 150 Yamahas

Thanks for the followup,<br /><br />I don't mind doing it all now, just thought that a little work and parts every year vs. a bunch of stuff every few years would provide the same result. I don't mind paying for the correct maint at all, much less expensive than the alternative. Maybe its better to keep both motors on the same sched.<br /><br />Yes, this grady has a large deck panel aft that need to come up to access the oil tanks. There is the typical crappy 6" round access hatch that allows filling the tank, but it won't allow servicing, and it leaks to boot. I might replace that with a bigger access panel.<br /><br />This boat runs mostly in Buzzards Bay and Cape Cod bay. I bought it in Nantucket where it spent the previous 5 yrs or so. May 1 - November 1 is a good year, 60-70 hrs is a very good year.<br /><br />For this year, I'll do both sets of water pumps, fuel pumps, clean oil pumps and filters, and service tstats/poppits/grommets. I should be good for a couple years (maybe a carb cleaning in between). Have you had good results with SeaFoam? Also, my carb rebuilding experience is limited to my 8 cyl snowblower 4 stroke motor. Is this something that I should consider tackling? I have a decent shop and a good set of tools, it seems pretty straight forward. The only thing that concerns me is adjusting the carb after its put back together. <br /><br />Thanks again for the advice!

 

[fastkenny]

Re: spring maint planning for old 150 Yamahas

oops! i meant 8 hp snowblower! an 8 cyl snowblower is what you find at the airport up here!

 

[rodbolt]

Re: spring maint planning for old 150 Yamahas

if you have never done yamaha carbs you will need two voodoo priests, a witch doctor, a shaman and maybe a buddist monk.<br /> naaaa just kidding. <br />leave the monk alone.<br /><br />that motor has three two barrel carbs. each barrel feeds a cylinder. take careful notes when dissasembling. I usually back off the idle speed screw 3 turns before removing. then remove the carbs. its best to push the hoses off the bowl inlets rather than pull. sometimes I work a thin small screwdriver blade under the rubber to help break it free. when you get all three on the bench make careful notes as to the size of the mainjets in each bowl. sometimes they are odd sizes and if they are they must go back in the same location. now we remove all the fuel bowls. remove the main jets(12mmhex) carb drains(10MMhex) and the idle fuel jet plugs ( small brass slotted screw).<br /> dont lose the metal washers under the idle fuel plugs, they dont come in the rebuild kit, however spare fuel bowl screws may . I dont try to remove the idle fuel jets unless I have to. they are small and easy to break/destroy. soak the bowls in some carb cleaner. remove the orings from the main jets and soak them to. on to the carb body. remove the floats use a piece of cardboard to lay them on in order. helps on reassembly, usually if the same float goes back in the same spot you wont have to adjust them. float height is measured with the bowl gasket in place carb upside down and from the gasket to the top of the float. .630" plus or minus.02". on the body. I remove the two small brass slotted pugs inside the throat. I usually dont remove the idle air jets. the two small jets at the upper outer edge of the throats. remove the idle fuel screws and the stainless plate. I usually dont remove the two large brass plugs at the top rear of the carb unless its been under water. I have seen many break the casting when removed after so long.now soak the bodies for 20 min or so. remove all parts and wash with water. blow out with air. then blow out with spray carb cleaner, the super tech brand works good. now blow out with air again. reassemble with new gaskets and needles. set mixture screws at 1 1/4 turns out. install the carbs. install the throttle links. loosen the carb sync screws. they are left hand thread but if you look they are marked.while holding the bottom shutter closed tignten the synch screw then do the top. I dont know which oil pump you have. follow the procedure in your manual to insure its set correctly. some of the old kien pumps set at WOT and the mikunis with the pump arm closed and the throttles fully closed. now turn the idle screw back in 3 turns exactly. now set the throttle roller inline with the mark on the cam ( sometimes the cam must be disconnected to perform the first 3 steps) now make sure all cam,throttle,choke and OIL. repeat OIL links are installed. prime the system and fire it up.<br /> its imperative to identify and properly check/adjust the oil pump. the 88 originally had a pump with 6 nipples in a circle pointing up (kien). the conversion pump has 6 nipples 3 pointing fwd and 3 pointing aft (mikuni). I think the two set up differently but memory is muddy.follow the manualif any steps are different from above. like I say memory gets muddy. but thats about the low down and skinny of it.

 

[fastkenny]

Re: spring maint planning for old 150 Yamahas

Wow, thanks for the detail and all the potential gotcha's!<br /><br />I'm going to print that out and staple it to the carb section of my manual.<br /><br />I'm hoping to get started in a few weeks, I'll let you know how it goes. In the meantime, I'll be shopping for fuel pumps and water pumps.<br /><br />thanks again

 

[rodbolt]

Re: spring maint planning for old 150 Yamahas

I can hook you up with a dealer here if you wish.<br /> I dont deal in parts I just fix them but several dealers in my are have been known to discount yamaha parts sold on order.<br /> I gave up parts and inventory years ago, not enough time for both. had a business partner and an employee once. never again.

 

[fastkenny]

Re: spring maint planning for old 150 Yamahas

thanks, any dealer info is appreciated.<br /><br />I'll check with dealers in this area also.<br /><br />BTW, how is a leakdown test done? I understand it tells more about the condition of the engine than just a compression check. The clymer talks about it, but doesn't say how to do it. Any special tools needed other than compression guage?<br /><br />thanks