'86 4.3L OMC Stringerdrive runs to almost 200°

[86 4.3L OMC Stringerdrive]

I bought an '86 4.3L 4-Barrel with OMC Stringerdrive. Has new 170° thermostat, impeller was replaced 12 hours ago I am told...just installed new Marine water pump on block...starts fine...sounds fine...not dripping water like a freeze plug issue...fire it up...runs straight towards 194° ( 9C on gauge) within 4 minutes...so I shut it down...always garaged...only 488 hours on boat...maybe pull impeller to see if it crapped out?? I need advice...should I let it tap that 200° line...does it need to run up, before thermostat opens using Muffs???...if I pull lower unit to check/replace impeller...is there a good video online for impeller replacement on Stringerdrives?? Thanks in advance!!!

 

[dubs283]

I personally have never replaced an impeller on those drives. I do know the impeller is big and floppy and rarely fails

I would question first the installation, then inspect for blockages in the cooling system, mainly between the pump and t stat housing. Is there any water coming out the exhaust, outside the boat?

I'm quite sure the thermostat for those engines is most likely a 140 degree, not 170

 

[86 4.3L OMC Stringerdrive]

With Muff hose on...hard to tell if exhaust water is hitting ground...i saw a completely unrelated thread...where they checked hose coming FROM impeller to motor...i will check that tomorrow....
Thanks Dubs

 

[Scott Danforth]

Pull the drive apart.

Buy a complete new raw water pump assembly

Grease the pivot shaft

Replace the now burned exhaust rubber bits

 

[86 4.3L OMC Stringerdrive]

I bought an '86 4.3L 4-Barrel with OMC Stringerdrive. Has new 170° thermostat, impeller was replaced 12 hours ago I am told...just installed new Marine water pump on block...starts fine...sounds fine...not dripping water like a freeze plug issue...fire it up...runs straight towards 194° ( 9C on gauge) within 4 minutes...so I shut it down...always garaged...only 488 hours on boat...maybe pull impeller to see if it crapped out?? I need advice...should I let it tap that 200° line...does it need to run up, before thermostat opens using Muffs???...if I pull lower unit to check/replace impeller...is there a good video online for impeller replacement on Stringerdrives?? Thanks in advance!!!

UPDATE:
I can't figure out editing....so...
IT'S FIXED!!! Replaced impeller that was smoked...replaced engine water pump (don't know if it needed it)...still ran straight up near 200°...replaced thermostat previous owner said was new...NOT!!!...and backed it down ramp still on trailer at Wimpy's...fired it up...gauge crept to just east of 160° on gauge...and just stayed there...
....
Pulling lower unit to R&R impeller in bottom of upper unit was tedious...but a pro-mechanic bud mastered it....HOWEVER...a HUGE shout-out to Kenny Nunez who helped us out every step of the way...could NOT have done it without his knowledge and answering our stupid questions & pointing us in the right direction....THANKS KENNY!!! You ROCK!!!!...Shout-out to iboats...great forum....Thank you to all who offered advice...
Gnite...Mike

 

[86 4.3L OMC Stringerdrive]

 

[Lou C]

OMC used a 160* thermostat so that’s just about right.
I have those same Medallion gauges and they all still work. 75* C (top scale of numbers) is about 170. Mine never goes over 175 (80*C) as long as all is well.
Replace your impeller every 3 seasons and you should be good.