250XS still overheating on long idle?

[fasterbasser]

hey guys,

I had a thread on here about three weeks ago about my 250XS overheating when I'm graphing for more than about 10 minutes. So I replaced the entire water pump assembly, and I still have the problem. Is the next step the poppet valve or the t-stats, or both (where is the poppet valve?). Another question I have is do I maybe have the motor jacked too high? It's 3" below the pad, as suggested by the setups forum here on BBC. Any help would be greatly appreciated, as the season is getting ready to get started, and I would love to get rid of this minor pain!

[taeheel2az]

What's the pressure with the new WP? If you have SmartCraft guages did you watch the water temp as it rose? If not, seriously consider getting a mimimum set. Unlikely the motor is too high since this occurs at idle, assuming you're trimmed down.

First steps first.

Test the T-stats - you'll need new gaskets from Don, and be sure to clean <u>all </u>the old gasket material off them. While you're at it, get a handful of the Merc tie straps from him. I don't know at what temp those T-stats should open. BTW, they don't open a whole lot. And it only takes a tiny amount of blockage to keep them from working right.

Inspect the in-line plastic screen that's inside the middle housing on the lower aft port area of the engine - a black line runs from there to the bottom of the port fuel rail. Unfasten it at the block (don't yank on it, you can break the plastic fitting on the fuel rail) and slide it out.

If you're OC like me, put ear muffs on the engine with water running and crank the engine. Within 30 - 45 seconds, water should gush out the opening.

If all this passes, put the screen back and reconnect the line. Again, with ear muffs and water on, crank up and see if there's good flow from the tell tale in about 45 seconds. If not the tell tale line may be plugged.

If all that's good, might be time to check out the poppet.

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by taeheel2az &raquo;</td></tr><tr><td class="quote">What's the pressure with the new WP? If you have SmartCraft guages did you watch the water temp as it rose? If not, seriously consider getting a mimimum set. Unlikely the motor is too high since this occurs at idle, assuming you're trimmed down.

First steps first.

Test the T-stats - you'll need new gaskets from Don, and be sure to clean <u>all </u>the old gasket material off them. While you're at it, get a handful of the Merc tie straps from him. I don't know at what temp those T-stats should open. BTW, they don't open a whole lot. And it only takes a tiny amount of blockage to keep them from working right.

Inspect the in-line plastic screen that's inside the middle housing on the lower aft port area of the engine - a black line runs from there to the bottom of the port fuel rail. Unfasten it at the block (don't yank on it, you can break the plastic fitting on the fuel rail) and slide it out.

If you're OC like me, put ear muffs on the engine with water running and crank the engine. Within 30 - 45 seconds, water should gush out the opening.

If all this passes, put the screen back and reconnect the line. Again, with ear muffs and water on, crank up and see if there's good flow from the tell tale in about 45 seconds. If not the tell tale line may be plugged.

If all that's good, might be time to check out the poppet.

</td></tr></table>

VERY good advice.

[fasterbasser]

Thanks taeheel2az and Don, I will do all that this weekend and let you know. If all that checks and I do need to look at the poppet, where is it and what am I looking for to check it? BTW, how much are the Smartgauges, and is it something I can plug in? I'm a fairly descent mechanic.

[SleepDR]

Modified by jericbarg at 7:25 PM 2/8/2012

[taeheel2az]

SmartCraft has many options. The key choice IMHO is a monitor which displays, among quite a few other options, water temp, faults, fuel usage, and motor hours. You can keep the guages you have now, except one choice is to get a Speedo or tach combined with the monitor. I don't know the exact cost of this setup, but I'm thinking 4 or 5 hundred. I was a Yammie guy before this engine, now I'm 50 / 50, but I'll never have another high powered engine without SmartCraft or equivalent. Very straightforward to install.

The poppet is on the lower starboard side of the motor, the cover is round with two ears where bolts attach it to the motor. Best to take off the lower cowling to get access - it's possible to remove it without doing so, but it's cramped and you run the risk of knocking the grommet off the end, which falls into a water chamber, then . . . well, take it from me, best not to do that.

The poppet assembly should slide out smoothly with just a skosh of rubbing friction. Before re-inserting, make sure the grommet fits snugly and turns smoothly on the flange on the end of the poppet assembly. You'll be looking for ease of removal and replacing, a torn diaphragm, debris, anything coating the spring, condition of the grommet, etc.


Modified by taeheel2az at 7:06 PM 2/8/2012

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by fasterbasser &raquo;</td></tr><tr><td class="quote">Thanks taeheel2az and Don, I will do all that this weekend and let you know. If all that checks and I do need to look at the poppet, where is it and what am I looking for to check it? BTW, how much are the Smartgauges, and is it something I can plug in? I'm a fairly descent mechanic. </td></tr></table>

Rhonda (in our Parts Department) would be more than happy to assist you with the components needed for both projects.

See the following post for contact info (it's also pinned at the top of this forum, for future reference):

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

[fasterbasser]

Thanks to both of you!!! It's all great info, I will check out the entire cooling system this weekend and am already looking for the tach and speedo with Smartcraft. I will get a quote from your folks Don. Thanks again!

[poeman]

Mine was doing that and it had sucked a piece of wood all the way to the thermastat it would only go off at idle or a little faster.