DT140 water pump mistery

[tybee2]

the DT140 is a straight 4 cylinder so there are some differences in the cooling/flush systems.

[tybee2]

OK. finally a report:

dissected the foot.
had lots of fun getting the screws out of the drive shaft bearing housing and then getting the bearing out.
managed to break off part of the housing so i had to order another bearing housing assembly.
at least it came assembled with the oil seals/O-ring already installed.

after breaking the casing and getting it off, we found the wall between the exhaust port and the water intake chamber was about gone on one side.

got the remnants of the wall cleaned off with the dremel and repaired the wall
with a product called Belzona (a metallic polymer) that was like a thicker JB Weld. it was fairly easy to work with (kinda like peanut butter) and it didn't flow like JB would have.

eventually got the foot back together with the new bearing housing, grommets on the tube, etc.

now it pees like the proverbial race horse.

but...

now, when running it about 4k rpm for several minutes, the motor slows down to under 2k rpm but no rev limiter alarm nor temp alarm goes off.
there is a bit of steam out the exhaust port at the back of the motor but the pee stream is merely warm and not blisteringly hot like it was before the rebuild.
i can continue to idle along, the steam disappears and then i can run for another 4 or 5 minutes and the same thing happens: engine slows down to 1.5k rpm or so, a bit of steam appears, no alarms or idiot lights show up and the tell-tale stream is just where it ought to be as far as temp and strength goes.

what would cause that sort of behavior?

[Solarman]

Do you have a laser temp gun? It sounds like you still have overheating going on? I'm not sure why the monitor isn't showing a temp alarm, do all the lights on the monitor light up when you turn key to the first position? Your motor seems to be limiting rpms for the overheating, this is good.
How old is the thermostat, could it be sticking? Or not opening fully?
You should be getting water flowing from the exhaust port at back of motor, not steam.
Use a laser temp gun to see if any areas around each cylinder show overheating.
Have you ever changed the thermostat? If not be prepared, those bolts may break off, be careful.

You could try running with thermostat removed, to see if you get more water out the back exhaust port, instead of steam. If still getting the same problem, let us know.

Good luck, post us back with the info.

[tybee2]

i replaced the thermostat back in the spring and visually inspected it when the overheat issues first showed up a couple of months ago and the thermo looked normal. the one i had replaced looked ok, too, it's just something i do every other year.
i believe i have a spare one and that's an easy thing to replace.

the temp and rev limiter idiot lights do come on when i first turn the ignition on and go out after a few seconds, just like they always did.

i'll change the thermo and report back.

now off to annoy the neighbors to see if one has an infrared temp gun...

what kind of temp would be "out of the normal" on the head?

[Solarman]

Tybee, I did ask if it had been changed. I asked you to report back. The problem might not be there, and I'm trying to help locate your problem. So I'm asking some questions, because I can't be there to see what you see. It isn't easy on this side of the forum. You have to be our hands eyes and ears for each problem your motor has.
Now, you mentioned the deterioration of the wall under the water pump. And I'm concerned if there might be some blockage, or other deterioration in some of the water pas-sages?
I think a laser temp gun is the next step (can get at auto parts, or harbor freight, for under $30.).
Start the motor on ear muffs, idle it up to 1800-2000 rpms and start checking the Temps around each cylinder, see if you find any areas that are hotter than others. Also check areas around the exhaust cover plate.

Good luck, and let us know what you find out.

[tybee2]

i REALLY appreciate your knowledge and expertise and your help.

the only place the walls/dividers were corroded was in that area around where the under tube grommet/gasket went. the rest of the foot looks fine and where it mates up to the upper half and the upper parts themselves show no deterioration at all.
i guess it's possible some part of the lower area came loose and ended up somewhere in the head. i hope not as my skills do not go as far as dissecting that.

i'll report back after i locate an infrared sensor and check the temps out.

how hot will the engine get? how hot is too hot? i'm sure certain parts will be warmer than others but how do i tell if a temp is a problem?

[Solarman]

If you have steam coming out of the back exhaust port, the motor is overheating, as I read what you've stated.
If you have a good tell tale stream your water pump is working. But you either have a blockage, or you may have another area where the exhaust is pushing water back from getting around the cylinders. If it is around the cylinders, they'll be too hot to touch, the laser temp gun can help locate where the motor is getting the hottest, it may tell us where to look.

Post back what you find out. Good luck.

[briscoe]

I had issues with cooling on a DF140

Although I don't have the same motor, I was having some cooling issues on my motor. Nothing helped changing impeller on water oump. I began disconnecting the outlet side of each water supply hose and found one plugged. Never had another peoblem. You can get a copy of the water supply hose routing on this site when you search parts on specific engine.
Just my two cents

[tybee2]

I finally got an infrared heat "gun".
i need better friends and neighbors 'cause either no one had one or they didn't have one that functioned.
sigh.
so i had to go buy one.
the wife, who is reasonably mechanically minded, after examining the water flow pattern for the DT140 said it might help flush any small "disintegrated wall" parts out of the cooling jacket if we removed the thermostat and flushed the motor as thoroughly as possible since the thermo was closest to the top of the engine and would let a lot of water out a less restricted passage and might perhaps flush out anything wandering around in the cooling passages.
finding no particular flaws in that plan, we did so.
nothing that we saw came out so i put yet another new thermostat in place, put the ears on and cranked it up.
running at around 1800 to 2000rpm for 15 to 20 minutes, the infrared instrument said:

on the back of each cylinder where the spark plugs live, the cylinders were all within a couple of degrees of each other at 118 to 120 degrees F.

on the exhaust cover side, the top cylinder got to about 150 degrees, the one below it at 145
the one below that at 110
and the bottom one at 110.

the temps stayed right there for the last 10 minutes or so of fast idle.

i boiled the old thermo and it started opening at 120 degrees.

no alarms, no rev limit light, no nothing in particular noted.

so, unless those numbers are way out of whack, i guess the next step is to float the beast and take a ride to see what happens.

what say ye all?

[artdf175]

Open Water testing is preferable
I am thinking the thermostat I have is 140 degrees
So 140-150 is not out of line
Earlier you indicated you ran it at 4000 - and then it dropped back to 2000
Was that open water or on the hose? It could be the rev limiter kicking in
I am thinking that 3000 is the best you can do without putting it in gear
And since I have not re-read the thread there have been a number of times people have overheating problems when on a hose- my mechanic recently showed me that there are two holes between the leading edge and the screened intake and you need to put muffs over those two holes as well as over the screen
When running out of the water
Art

[tybee2]

the "slow down" occurred in open water.
but no temp alarm lite or horn, no rev limit idiot light.
many things have been attempted to diagnose/cure that symptom.

[Solarman]

I would consider running a corrosion flush, using a large trash can, or other container (can run 5-8 gals of vinegar for a good couple hours ). Your Temps should not reach 150°f. It appears there may be some blockage around the upper cylinders water pas-sages.
Watch the Temps while running after an hour. Your motor should be running about 110°f- 120°f. This is a dt140, not a df 4 stroke.
If water in container gets too warm, let it cool down a couple hours to run again. Do this in stages for 2-3 hours, until you notice some temp changes.
Post back how is going. Good luck.

[Stu789]

Hi all,
I got the parts and replaced the water tube sealing parts (both ends) without removing the bearing cap (had to slightly flex the heat shield to remove it). I also gunked everything up with high temperature gasket maker. It's all together, but the boat is out of the water and winterized (fogged down). Won't be able to test it until next spring. Sorry for the long delay in responding (busy with travel).
Stu

[tybee2]

after scrounging a barrel, several gallons of vinegar, running the engine several times until the "coolant" got warm, letting it cool and repeating (BTW, warmed up you can smell vinegar several blocks away). the cooling problem remains.
so, i decided to take the exhaust cover off and take a look inside.
good news was that there was a spongy piece of something that was caught up in the cooling tube that led to the top cylinder.
bad news was that i snapped off 3 bolts getting the cover off which means i can't see if that piece of reed/rotten wood/whatever was truly the issue.

so the endeavor goes on...

[artdf175]

bolts.. yes they do twist and break
get an extractor tool..
these have a drill on one end and the extractor on the other

center punch the bolt.. the drill is a reverse drill
drill the center
turn the extractor bit around and again reverse drill it
the extractor bites into the hole you drilled
never had one not come out

if there is enough of the bolt to grab it with vise-grips, try that first..
Art..