New Boat- WOT speed, RPM and water temp questions

[Ski-me]

Did you get a 160 stat?

https://www.skidim.com/prodinfo.asp?number=R026002

[Bartnich]

Did you get a 160 stat?
https://www.skidim.com/prodinfo.asp?number=R026002

Yep, I’m going to install it tomorrow as well as clean the fuel pump inlet then take it out one last time this weekend and see if it makes any difference. It gets really cold here on Monday night so this will be the last water test til spring...

[mikeg205]

Careful with that 160 stat... does not fully open till 160 and heat soak can take you to 180+. every thing seems to work until hot restart.. motor turns and turns... temp drops... starts fine.. 143 is spec'd... motor runs 160.. but wont heat soak as far... hot starts are fine then.. there threads on this

Sent from my SM-G955U using Tapatalk

[Bartnich]

Careful with that 160 stat... does not fully open till 160 and heat soak can take you to 180+. every thing seems to work until hot restart.. motor turns and turns... temp drops... starts fine.. 143 is spec'd... motor runs 160.. but wont heat soak as far... hot starts are fine then.. there threads on this

Sent from my SM-G955U using Tapatalk

Thanks Mike. Now it appears I have both a working 160 and a working original 143 so I should be covered either way. I really want to see if the higher water temp helps. Still not sure if I will be able to see higher temps if the raw water is in the low 50s.....

[mikeg205]

Been there.. a good tstat will keep you at operating temp.. order extra gaskets[emoji1787][emoji1787][emoji1787]

Sent from my SM-G955U using Tapatalk

[Poorhouse]

OK, reviewing the '96 MC TBI manual. No indication RPM is limited based on engine temp. Just says it allow richer mixture until up to operating temp.

There is a 20 step diagnostic process for "lack of power, sluggish or spongy symptom". I think your inability to hit max RPM would fall under this category.

I can upload pics if needed.

[Bartnich]

OK, reviewing the '96 MC TBI manual. No indication RPM is limited based on engine temp. Just says it allow richer mixture until up to operating temp.

There is a 20 step diagnostic process for "lack of power, sluggish or spongy symptom". I think your inability to hit max RPM would fall under this category.

I can upload pics if needed.

Sure, upload pics if you can. I will check through the list and see if anything might be the culprit. Thanks!!!

[waterlogged882]

Sure, upload pics if you can. I will check through the list and see if anything might be the culprit. Thanks!!!

http://www.mastercraft.com/manuals

[Ski-me]

Careful with that 160 stat... does not fully open till 160 and heat soak can take you to 180+. every thing seems to work until hot restart.. motor turns and turns... temp drops... starts fine.. 143 is spec'd... motor runs 160.. but wont heat soak as far... hot starts are fine then.. there threads on this

Sent from my SM-G955U using Tapatalk

Skidim recommend the 160 to be ok though.

[mikeg205]

They did same for me.. and i got in a jam years ago with a barge bearing down on me and i couldnt start... oem was 143.. yeah runs better with a 160... but that no start when hot was a bit scary...

Sent from my SM-G955U using Tapatalk

[Ski-me]

They did same for me.. and i got in a jam years ago with a barge bearing down on me and i couldnt start... oem was 143.. yeah runs better with a 160... but that no start when hot was a bit scary...

Sent from my SM-G955U using Tapatalk

OK, THAT'S no fun!!

[Poorhouse]

Sure, upload pics if you can. I will check through the list and see if anything might be the culprit. Thanks!!!

[88 PS190]

They did same for me.. and i got in a jam years ago with a barge bearing down on me and i couldnt start... oem was 143.. yeah runs better with a 160... but that no start when hot was a bit scary...

Sent from my SM-G955U using Tapatalk

My experience - 94 TBI - the 143 is fine but the boat runs cold the whole time and I swear burns more fuel (rich). What I prefer to do is to never shut the boat off right after a run. Coming down the lake pulling a skier, they cut you idle back to the skier, at this point lots of people shut off the engine - which is great thats safe - but thats exactly when you'll have heat soak, the temps will climb and you'll have a hot manifold/tough restarting.

However if you just pop out the neutral knob and bump up the RPM a bit for a minute you'll see the temps of the engine get pulled way down and the engine won't heat soak so high. Basically you're just giving it back the water flow of higher RPM with out giving it the load so you get the thermal mass pulled down.

Ideally they'd have this sorted a bit more but the tactic works.


Also - sometimes that thermostat test can be a bit... misleading, some thermostats seem to be fine when you take them out and fiddle with them/clean them but have junk in them and get sticky.

[mikeg205]

You hit the nail on head... safety

Sent from my SM-G955U using Tapatalk

[JimN]

Alright, here is another head-scratcher. I went and got a new OEM thermostat and compared it in boiling water to the old one. It appears they work exactly the same, meaning that the old one still works. So now the question is- Can there be enough by-flow of water when the thermostat is closed to keep the engine temp no higher than 130? Granted, the water is pretty chilly- around 53 degrees.....

Try to open the thermostat manually- if the old one opens more easily, replace it.

Have you cleaned out the oil cooler? Lack of water flow could cause air pockets in the cooling system and as I wrote before, the ECT is made to be immersed in water, not air. Is the impeller new? If not, and I don't remember seeing that it was replaced, get a new one and make sure the cooling system can't suck air in.