SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: 90ultra21lx on June 05, 2017, 08:43:03 AM

Title: BBC runs great but jumps at least 20 degrees in no wake zone
Post by: 90ultra21lx on June 05, 2017, 08:43:03 AM

Hey everyone! So over the off season we had tons of work done, new interior, stereo, motor got pulled, new jet, new transom, new msd ignition system to replace Mallory, motor went back in no upgrades just pulled out serviced put back in, after working out few kinks boats running great but last trip at havasu motor temp would jump 20 degrees almost immediately after pulling into no wake zone after a 20 min cruise at like 45 mph not floored it by any means... even before all the work, gauge always has motor running at 135-140 which I thought is cool so at the no wake zone it jumped to 160 immediately so I opened the hatch and it seemed to cool back off, should I b concerned it runs so cool? Maybe faulty gauge? I am having issues with other gauges, speedo n tach went out last trip, speedo always been temperamental and I had em replace the speedo mechanism on the transom still nothing... thanks for all your help guys! I'll post pics of all the upgrades later today!


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Title: Re: BBC runs great but jumps at least 20 degrees in no wake zone
Post by: 90ultra21lx on June 05, 2017, 08:43:59 AM

 It definitely didn't jump up last year before all the upgrades but nothing done to motor so kinda stumped


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Title: Re: BBC runs great but jumps at least 20 degrees in no wake zone
Post by: Brad @ SCJB on June 05, 2017, 08:45:39 AM

Totally normal. The water flow is coming from your jet pump so the water flow is slowing down dramatically​ when you come off plane. A 20° jump is totally normal and nothing to be alarmed about.

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Title: Re: BBC runs great but jumps at least 20 degrees in no wake zone
Post by: 90ultra21lx on June 05, 2017, 09:27:47 AM

I guess I never noticed it last year then? Thanks for the reply Man! Love what u do for the community Brad!


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Title: Re: BBC runs great but jumps at least 20 degrees in no wake zone
Post by: mash on it on June 05, 2017, 04:14:03 PM

A slightly higher idle speed can help, too. My heavy azz 21'er idles ~950-1000 rpm.
Helps around the docks, too

Dan'l

Title: Re: BBC runs great but jumps at least 20 degrees in no wake zone
Post by: Bonzen on June 15, 2017, 12:17:42 PM

No big deal dude. Thats actually better, when you are idling you are probably not burning off the carbon in the cylinders as much as when you are WOT. So a little hotter temp will help with that. 160 is still cold. Thats like before the Tstat opens in 90% of cars and trucks.

Mine does the same thing. Around 110-125 cruising deep water and then like 145-160 in warm stagnant water idling. Im not running a Tstat either.