Merc 470, No start questions

[BOBNEWTON]

Howdy,

Have a new to me Merc 470 MR1. Had it on the lake, it worked dandy except ran hot. (did not overheat it). Repaired a few issues, stat, rad cap, clean/flush and a new water pump in the lower.

After all this the engine fired quickly, ran in neutral, switched into forward then died coming back into neutral. It has not started since. The boat lost all spark, after some looking and testing, i believe it to be in the shift interrupter.

What is the best way to remove the leg and re align everything on the sift circuit, find neutral on both shift control and leg and reassemble.

I feel something is out of time in the shifter? I will do more diagnosing when I'm off work this week, however I'm pretty certain my issue is in the interupt circuit.

Is there a write up on realigning a shift shaft and control?

Thanks a bunch!

 

[BOBNEWTON]

I should not this is all on muffs as well. It worked totaly fine on muffs prior, and in the lake prior to lower unit removal. I suppose a lower cable being tight may be a contributing factor, but not the only issue.

 

[Bondo]

Is there a write up on realigning a shift shaft and control?

Ayuh,..... Welcome Aboard,..... There's several write ups, 'n videos in the Adults Only Section,......

Most likely cause is the lower shift cable is worn out,.....

 

[Scott Danforth]

if your motor ran more than 10 degrees higher than the thermostat, it overheated and may have spit the head gasket.

you ran hot, therefore you did overheat.

most likely your impeller is gone - it was probably bad before you bought the boat. and that 10 degree rise in temp I mentioned caused the aluminum block to expand more than the iron head and your head gasket may have suffered.


with any new to you boat, you need to do all the maintenance prior to going boating

this includes

new raw water pump assembly (yes, replace the whole thing, not just the impeller)
new bellows
inspect the gimbal bearing
inspect the u-joints
outdrive gear oil service
alignment

moving to the inside
clean out the heat exchanger (raw water side)
drain the coolant
perform a cooling system leak test
perform a compression test
new oil and filter
new fuel filter
service the points - file the points, adjust the gap, verify dwell, set timing

then move to the trailer:

service the wheel bearings
service the brakes
service the coupler
inspect the bunk wood or rollers, repair as needed

since you mentioned it died going into neutral, adjust or replace the lower shift cable

since you have a 470, read up on the following: speedi sleeve repair of cam snout, alternator conversion, upgraded heat exchanger, aluminum exhaust elbows, head gasket replacement

the information you will be asking for next is all in the stickies at the top of the forum. start there

there are videos and information on servicing the raw water pump in the outdrive
there is information on alignment
there are write-ups on the 470
there is troubleshooting and adjustment of the lower shift cable
there is troubleshooting and servicing guides for points type ignition.

 

[Rake722]

Scott’s advice is bang on - still working on mine 10 years after buying it

 

[BOBNEWTON]

Awesome guys, it was definitely the switch. Will need to replace cable when dong lower unit maintenance for sure.

I will disagree that running 180* on a 160* thermostat would be considered an overheat. The rating on a tstat is stating cracking pressure, it will not be anywhere nearly fully open at that temp, and it wouldn't make sense to expect no hotter than 160.

 

[Scott Danforth]

Awesome guys, it was definitely the switch. Will need to replace cable when dong lower unit maintenance for sure.

I will disagree that running 180* on a 160* thermostat would be considered an overheat. The rating on a tstat is stating cracking pressure, it will not be anywhere nearly fully open at that temp, and it wouldn't make sense to expect no hotter than 160.

if your motor was anything other than a 470, I would agree.


the whole floating bore/aluminum block/iron head issue makes the 470 a bit fragile on cooling.

 

[Benny67]

Scott’s advice is bang on - still working on mine 10 years after buying it

Agreed...Listen to his advice. He knows the 470's. I've been coming here for 5 years and he's been dishing out solid advice on these evil engines and has always been correct.

Under no circumstance let that engine run over 160'F. That is the #1 rule of the 470.

The design of the block in conjunction with the head (aluminum/cast iron) doesn't allow for temperatures over what the thermostat allows for very long.

I've been running 2 of these evil engines for 5 years now in my 27ft Carver. I have come to a love/hate relationship with them. When they run correctly, they are powerful,reliable and economical on fuel. But when they don't,well, just read all of the posts on how everyone hates them.

When you treat them right by paying attention to all their quirks, they will treat you well. If you DO NOT....well, then you will understand why 99% of the boaters hate them.