Normal Operating Temp M35

[cmainprize]

Looking for some info on the normal operating temp for a M35.  The Manual says normal is 165 to 195.  We usally run around 180 at 2100.  The boat is still fairly new to us and 180 has always seemed a little high for a engine speed of only 2100.  My M25 ran seemed to sit around 170. 
I fried an impeller yesterday just as we entered the point of no return in the marina.  The high temp alarm sounded just as we got into the slip.  Changed the impelller today (what a silly design) and went for a test run.  Lots of water from the exhaust but temp was running at 195 at 2100.  Had to limp it in to keep the temp down.  I was unable to find all the impeller vanes.  I got three out that were jammed in the pump casing and lots of little pieces.  Every vane was torn off the impeller.  I suspect it was on the verge for quite some time.  I was hoping luck was on my side and the rest went out the exhaust.  No such luck.  I will start the hunt for the rest of the pieces tomorrow. 

I was just wondering what temp the other members find there engines run at at say 2100 to 2500 rmp.
I was also wondering if the gaskets on the clean out covers on the HX are reusable once they are removed. 

Thanks for the advice.
Cory

[Jack Hutteball]

Cory, mine runs at 165 with rpm of 2600.  Has always run at that temp since new.
Jack

[chuck53]

What's the temp setting of your thermostat?

[Ron Hill]

Cory : The normal temp (with a clean HX) is 165/170F. 
You really need to find those other broken impeller blades.  The first place that I'd look is in the 90degree elbow of the exhaust from the Sherwood.  After that you might want to take an end cap off the HX and see what comes out - maybe some blades/pieces will flow out?     A thought   

[cmainprize]

Thanks guys
Not sure what the thermostat is rated at.  I can only assume it is original.  The bolts are still covered in paint.  We are a freshwater boat, I don't think our HX's are as prone to clogging up compared to you salt water guys.  But I have been wrong before.  I will start hunting for the missing blades.  Do you happen to know if I can reuse the gaskets on the HX when I put it back together.  I have no idea what kind of gasket is behind the cover. 

Cory

[Momentum M]

Cory...my temp is pretty constent...170 no matter at what RPM.

I've mentioned in a past topic that I was never able to keep the rad's overflow bottle with coolant in it.  I've checked everything that I can possibly think of and I see no sign of where it goes.  This is happening since day one (I bought new) and when I add to the bottle...within days it's gone.   
I've stopped wondering since the rad is always full, the temp @ 170 and doesn't overheat.

This Fall I'll be changing the antifreeze as it's to brown for my liking...even if it check to minus 50 or so.

Happy hunting for the missing parts as I also suspect that you have some restriction since before this mishap your running temp was in the normal range.

[Stu Jackson]

Do you happen to know if I can reuse the gaskets on the HX when I put it back together.  I have no idea what kind of gasket is behind the cover.

I wouldn't.  Do a search on Sendure and find out about gaskets and HXs.

The ONLY way you'll know what thermostat you have is by taking it off and reading it - temp is stamped on it in degrees C.  The temp of the thermostat will determine your running temp.

[Clay Greene]

My bet is that you have impeller pieces in your heat exchanger and that is reducing the water flow.  We had an overheating problem with the M25XP engine in our boat and found four impeller vanes that PO had failed to recover - one in the elbow off the water pump, one in the hose to the heat exchanger and two in the heat exchanger itself.  I would check all three locations.  We also had a bunch of broken zinc pieces and other crud in the heat exchanger that we cleaned out with a Limeaway bath.  Our engine temp went down from 185-190 to 165 where it has stayed ever since, two years later.   

[Ken Juul]

If it is the original thermostat it is probably a 160°.  Order or make new gaskets, don't forget the o ring.  There has been a recent thread about Heat exhangers with pictures.  A search should find it.  Pull the hose between the pump and the heat exchanger, take it up on the dock and wash it out with a hose, you may be amazed at what comes out.  Check the 90° fitting out of the pump to make sure it is clear.  Pull the ends off the heat exchanger and remove rubber bits from one end, broken pencil zincs from the other.  Put it all back together and see what happens.  Total time is probably less than an hour.  If you think it needs chemical cleaning try Ron's Lime Away method, it should show up on a search also, been discussed many times.  Don't forget to replace the zinc while your at it.

[Stewartn]

"I've mentioned in a past topic that I was never able to keep the rad's overflow bottle with coolant in it.  I've checked everything that I can possibly think of and I see no sign of where it goes.  This is happening since day one (I bought new) and when I add to the bottle...within days it's gone.   
I've stopped wondering since the rad is always full, the temp @ 170 and doesn't overheat."

Same story! 170 all day every day. But the antifreeze disappears from the bottle. NO LEAKS, trust me. If you open the radiator cap on the manifold (engine cold), anti freeze oozes (leaks) out as soon as the pressure cap releases. Asked the dealer and two mechanics. Got double talk. No problem. Just like to know what's happenin' down there. Any clues?
Thx/Rgds

[Ron Hill]

M35 engine owners: If you look in your Parts Book that came with the engine, on page 46 you'll find that there are 2 thermostates listed (items 13-1 & 13-2)!  Th differant thermostates are production year dependent.  Both are 160F , but have differant ODs !!

Amazing stuff in those engine manuals !

[Terry Forshier]

Over the past 5 months I noticed my boat running a bit hotter than usual. I thought maybe I needed the overfill reserve tank since I did not have one. I also recently had to install the riser for the muffler and had removed some of the antifreeze when I did that. But I had burped the motor and followed others advice and did not think that was the problem.. After all this I kept noticing an increase in the temp. I was checking to see yhe water flow and did notice it seemed less than I had remembered but thought it my inagination as there was water. Finally on a short run I started noticing "steam" coming out. I then saw the temp gauge go to 190 and keep rising. I backed off and thought maybe weeds on the prop. i jumped overboard and took a look. NOPE, all clear. Back on board i turned back toward home port. . the temp kept rising then suddenly the needle just slid back to normal range of 165 or so. I thought well, maybe the thermostat. Continuing on back it again began to rise. this time way up over 200 and even when i slowed it kept pretty high, but backed off some. It appeard that water was coming through but hard to tell leaning over the transome of a 1988. So made it in to dock ok. shut down, took off the orbendorfer face to check the imperller. OK. then went to thru hull , took off the hose at the strainer. Opened the valve. NOTHING>I sucked on the hose, with great sucking i managed a little water. ? not right at all. I took a wire and forced it down the tube and the valve, something crunched and the water came pouring in the hose into the boat. Hooked it all back up and now running with normal temperature. I must have had a barnacle or something like that either nesting in the opening or somehow lodged its self in it. So some times the simplest things.

[Stu Jackson]

Terry's right.  See Reply #2 and others here: http://c34.org/bbs/index.php/topic,4458.0.html

[cmainprize]

Thanks everyone for the advice and comments
I opened up the HX today and found lots of little impeller pieces.  See picture.  Moved on to the elbow on the discharge side of the pump.  It was jammed solid.  I can't believe it still pumped water.  Hose checked out fine.  Reassembled and tested to 2200rpm while tied to dock for about 20 minutes.  It pumped water like a fire engine.  Engine temp went to about 175.  I think being tied to the dock makes the engine work even harder but it seemed to be back to normal.  It will get a good test run this weekend to be sure.

Thanks Again
Cory 

[Clay Greene]

Glad you got it worked out.  Also, nice job on shredding that impeller - that is good and cooked!