04 250 hpdi overheating help!

[Slanglinais85]

Have a 04 250 hpdi that is over heating if you run over about 4500rpms. If you run at wot it alarm and shut down to lower rpms faster that if you run at say 4600rpms. When it alarms I shut it down and it looks like steam is coming out of the small exhaust port right under the engine cowling. It will run all day at 4000rpms but once you get into the higher rpm range it starts alarming. Lower unit was resealed last summer water pump and impeller were also replaced. T-stats are both working. I removed them and did a muratic acid flush which seemed to help it some. I am thinking i need to pull the heads and clean the water jackets. Has anyone else had this issue before? Or anyone have a write up on removing the heads for a 250 hpdi, i havent had any luck finding anything yet.

[ausnoelm]

Sure seems like the time to remove the heads and any other parts that will enable access to the water passages to clean them out properly. I can't believe you can't find anything about this fault!

[TownsendsFJR1300]

Agreed, sounds like the heads need to come off.

A shop manual wouldn't hurt but it's pretty straight forward R&Ring the heads.

(BTW, my neighbors 200 did the exact same thing. The lower water passages were 98% clogged with hardened salt. Once cleaning out(the head too), ran great, no more alarms. Actually, quite amazing it ran as good/as long as it did with that clog...)

[rodbolt17]

are you sure it is an overtemp alarm???

[Slanglinais85]

Yes its the temp alarm that flashes on the guage when buzzer sounds and yes it kicks it down to lower rpms (safe mode). I am very mechanically inclide so pulling heads shouldnt be very difficult. But where can i find the specs for torquing the bolts and also the gaskets and parts i will need for rebuilt? Sims have kit for that?

[TownsendsFJR1300]

But where can i find the specs for torquing the bolts and also the gaskets and parts i will need for rebuilt? Sims have kit for that?

The torque spec's are often stamped on the head itself as well as the order.

You want to order from the sponsor here, Boats.net. Their also part of Partzilla (a motorcycle parts supplier with VERY good prices...).

BTW, Pee stream will be the same even if clogged up darn near completely. Coolant is simply NOT flowing thru the passages due to being clogged up...

[Slanglinais85]

I did notice this weekend that when i was cruising around 3600rpms the water psi was reading around 10-12psi amd when i accelerated to higher rpms it would drop down to almost 0... but i dont think that guage was reading at all in the past....

[Slanglinais85]

Ya'll think this could be a cavitation problem at higher speeds with the water intake?

[99yam40]

air into the water intake means a problem, but not sure i would call that cavitation

[TownsendsFJR1300]

Ya'll think this could be a cavitation problem at higher speeds with the water intake?

Did the engine ever run upwards of 5,500 RPM's WOT (W/O any issues) ?

[Slanglinais85]

Yes it ran fine beginning of last season. Had an issue with it fouling spark plugs so i switched from yamalube to pensoil which solved the plug fouling issue. Then several trips after that i sucked up a bunch of sand i believe with cause it to over heat and was doing it at lower rpms also so i took it into shop they pulled t-stats and did a muratic acid flush which seemed to fix the problem for for short period of time then the running at high rpms for several minutes would cause it to over heat. Thats why im thinking mb some water ways are clogged in heads. And i had lower unkt resealed amd impeller replaced end of last summer.. problem still consistent after impeller was replaced. Just wanna get other peoples thought that migh have had similar problems if there is something simpler i can try before tearing it down.

[TownsendsFJR1300]

If there's sand in there, you may try pulling the anodes and either flush completely from there or pull the thermostat too and flush downward, draining OUT and anode holes...

They used muratic acid on your engine??? Jeez, that's really nasty stuff..

Here's a couple of threads using chemical cleaning should you want to try that first:

http://www.yamahaoutboardparts.com/f...g-th19434.html


http://www.yamahaoutboardparts.com/f...m-th23666.html

Post #21: http://www.yamahaoutboardparts.com/f...h27868-p2.html



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[Slanglinais85]

Where are the anodes located? I have already done a muratic acid flush from t-stats down and yes yamaha certified shop used a muratic acid/water mix to clean out build up.

[TownsendsFJR1300]

Whats the actual MODEL # so I can look up in the parts fiche?

2004, 250HP______

[pstephens46]

How many hours on motor?