Engine temp

[JayLaw]

Hey there Don or anyone else,
Got a question regarding engine temps. I am very observant when it comes to my water pressure and my engine temp and always allow for the engine to warm up and stabalize procedures before shutdown. Yesterday after motoring thru some very shallow water, i ran to my next spot, and all was fine I shut down for about 10 minutes to fish some offshore stuff, then started the engine back up and waited for temps to stabilize around 120 before getting on plane, they never came up above 81 degrees, which earlier in the day were coming up between 115-125. I noticed my wp was also lower at idle then normal as well. I figured i had some debris in one of the T-stats thus not allowing it to come up to temp. Brought the boat home and checked the T-stats and both had a few grains of sand in them holding them open less then about a 1/16th of inch. I reinstalled them and the temps returned back to normal and WP at idle was back to 2.9-3.1 psi. I was surprised at that little amount of water passage would not allow the engine to come up to temp.

I notice you have said some engines may only come up to 80-90 degrees depending on water temps and air temps. Water temps here were 39 degrees, though the engine came up to temps easily earlier in the day, and i am pretty confident it was that little bit of opening on the stats that were causing my problem.

When a known issue like this comes up out on the water what is a safe rpm range that the boat can be ran back to the ramp- asking in the event that next time it happens i wont be so close to the ramp? I cut my day short on the water cause i didnt want to run the motor with the stats not opening and closing properly. If temps are coming up to 80 degrees would it be "safe" to run the boat back to the ramp at a 3-3500 rpm range? Or can you still run it as normal? Or not run it at all?

Next question I know you have mentioned it here before, but what is the torque on the two nuts for the RH fuel rail? I bleed the system and had to back the nuts off about 3-4 turns to get the RH t-stat out and just wanted to make sure they are torqued correctly.

I will be replacing the water pump here soon as well, just to do yearly maintenance and will be calling you for some parts as well as a new fuel filter. Will probably order a few T-stats and gaskets as well just to have some on hand for the future.
<br /><br />
Modified by JayLaw at 5:41 PM 1/1/2012


Modified by JayLaw at 5:41 PM 1/1/2012

[taeheel2az]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by JayLaw &raquo;</td></tr><tr><td class="quote">. . . .both had a few grains of sand in them holding them open less then about a 1/16th of inch. </td></tr></table>

Yep, doesn't take much. That's about all the stats open, so the water flow through the stuck stats was about the same as if they had opened from hot water. I had the stat discharge hoses disconnected earlier this year so I could watch water flow, to try to diagnose a problem. I was surprised to see how little discharge water it took to drop water temp after they opened.

[EuropeanAM]

Jay:

With properly functioning thermostats, your engine SHOULD reach at least 120 degrees at idle (references to cooler temperatures are referring to ON PLANE operation... at RPM's higher than idle, in cooler water temps).

If engine does NOT reach 120 degrees: IDLE SPEED (1100 RPM's or below).

Keep a VERY close eye on those temps.... we've found that "sand" laden t-stats often exibit problems later, as small grains migrate to the moving portion of the thermister, resulting in scarring (and binding).

Rail attaching nuts should be torqued to 35 FT LBS.

Thermostat cover bolts: 100 INCH (yes that's INCH) lbs.

Water pump is certainly a good idea... as you know the debris you found in the t-stats had to PASS through the water pump.

[JayLaw]

Thanks guys!

[JayLaw]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by EuropeanAM &raquo;</td></tr><tr><td class="quote">Jay:

Keep a VERY close eye on those temps.... we've found that "sand" laden t-stats often exibit problems later, as small grains migrate to the moving portion of the thermister, resulting in scarring (and binding).
</td></tr></table>

Don now you have me wondering. Would it just be better to go ahead and replace the T-stats now when i change out the water pump? Im sure that the safest thing to do and wil eliminate any question of a sticking thermostat. Also any concern or need to check the poppet valve? If so where might this be located and how difficult to remove? There really was not more then a few grains of sand per thermostat... but i see it doesnt take much to cause problems.

If so send me an IM on how much for a new impeller/gasket, also four thermostats with gaskets (want to have a spare set). Also not sure which stats your gonna send me, the ones you replaced them with back in july when i stopped in were a higher temp rating (140?) then the stock ones we removed.

SN: 1B822550 Merc 250 Pro Xs

[EuropeanAM]

You would receive the later-design thermostats (if ordered).

In general, you should be able to monitor you temps carefully for one trip (primarily when at idle) to ensure you're achieving AT LEAST 120 degrees. If everything goes well that trip... continue to monitor NORMALLY (they're likely fine).

Drop an email to our Parts Department... we'll be glad to help you with whatever you should need.

http://www.bbcboards.net/zerothread?id=531508