DT140 water pump mistery

[Stu789]

Hi, I'm new to this forum and need help. I have twin DT140's (year 2000) and one was overheating. I replaced the water pump impeller (after market Sierra) and it would still overheat (good stream at 1k rpm, sputters at 2k, stops and overheats at 3k rpm, good stream reappears at 1k.). I put in a new OEM (Suzuki) impeller and had the same result. So I switched lower units of the two outboards. Sure enough, the exact problem switched engines. So, even though it seemed impossible, I put on a new OEM water pump housing. Still have the overheating problem. During the many, many, times I have removed the lower unit I have made sure all water pump input passages are clear and remain clear. I also replaced the seal at the water pump output. What else is there to do?

[Solarman]

It's not really that unusual.

Ok. What probably is happening is, exhaust is leaking into water pump chamber and pushing water out before water pump can pull it up. The higher the RPMs, the more exhaust interferes with water pump.

Does your motor have this sub water pick up tube? Some models didn't have it? If you have it (probably do), you'll need to get the new grommets, and a few other things. Will you be doing this yourself? Post back and let me know. while lower unit is off, look at the aluminum webs that separate the different channels. Notice if the mating surfaces are in good shape? If corroded and eaten away they should be repaired. These webs also prevent damages from hot exhaust gases.

There is a sub water pickup tube on my dt140's that goes across the exhaust chamber to under the water pump. Those grommets that seal that tube are burnt out, and need to be replaced. The parts are not very expensive, but you will have to remove the water pump assy. Then remove the flat stainless water pump plate (it might not clear the impeller key - remove the key from drive shaft). There should be screws/ or bolts under that plate. These screws (plus 2 nuts/bolts on outside of bearing cap holding grommet and heat shield in place) hold the bearing cap assy down. Remove key in drive shaft (if not done yet) for impeller, bearing cap is slightly spring loaded (just about 1/4”), but oring may hold till lightly pryed on both sides. once cap is up high enough, stuff a clean rag in hole around drive shaft (leave drive shaft in, just slide cap off (do not lose the spacers under bearing cap). Wrap bearing cap in clean rag.

Ok so post back and let me know if you're doing this work.

I don't want to tell all these secrets if you're paying a mechanic anyway.

Let us know. Post back.

[Stu789]

Thanks

Thanks Solarman. I will be doing this myself. Sounds like I will have to drain the gear case because of taking off the bearing cap. Your analysis seems likely. I do notice a lot of exhaust smoke coming up when the engine runs at higher rpms. So, if the water is being pushed back by the exhaust, have I ruined the new impeller? It looks ok. The motor does have a sub water pick up tube, and the gromet was protruding into the passage way so I cut some of it off (to clear the water passage way--wrong thing to do I guess). I never noticed any damaged aluminum webs, but then I wasn't paying attention to them. As I originally explained, I have removed the water pump body, impeller, drive shaft key, stainless steel plate (and gasket) several times. I have noticed the screws you mentioned, but never removed them, not sure what heat shield you are referring to, unless it is that plate just outside and in back of the water pump assembly--right over where the pick up tube gromet is located. Sounds like I'll need a new O ring too.

[Solarman]

Gather your parts, do not need to drain lower unit oil. Parts to replace sub water tube grommets, o ring for bearing cap, drive shaft seal for bearing cap, and if any of the bearing cap screws get damaged removing them, replace. Yes, the heat shield is on the sub water tube, and protects that grommet from exhaust, it is important to put back properly.

A simple couple of boards (2x6's) across two tall (same height buckets) is what I used to support my lower unit, and keep upright to keep oil in unit. It isn't hard to do this, but keep bearing cap clean and hole covered until reinstalling.

Under my bearing cap I had two spacers, they gave a little problem because they have to fit back into their grooves before drive shaft will fit down with spring load properly. If not in place, you won't be able to press bearing cap down all the way, just ease up and move shaft around and press down a few times, you should feel it hit just right and slide into place.

There is one screw and grommet at trim tab end of tube. none of the dealers near me had that grommet, so I just reused my old one (I did add a thin coat of silicone to help it).

The oring and drive shaft seal are the only protection keeping water out of lower unit, so it is a good idea just to replace them anytime you do this repair.

The stainless heat shield goes against the new grommet going into the cavity under the pump (I found mine were installed backwards, on both of my motors?)

Good luck, post back if any questions.

What area are you located in? And what type of boat are the motors on? I'm running twin dt140's on my 26' sea cat.

[Stu789]

Thanks again

Hi, I am located in Annapolis, MD and have the DT140's on a 25' Blue Fin (made in RI, very solid walk around w cuddy cabin + separate head). Will look for parts at iboats and boatersland, can you suggest any other places. Have company coming, so it will be awile before they are gone and the parts are here. Looks doable.

[Solarman]

Can order from brownspoint. Com online, they will send directly to you. The entire repair would take couple hours tops, if you're familiar with removing and re-installing the lower unit.
Having parts on hand when you take it down, means you can re-assemble after getting apart, and just work in reverse.

As long as you are a little mechanically inclined, and have a few needed tools, it should be easy.

And remember, if any problems you don't understand, cover it up (keep it clean), then post us what the problem is.

Good luck.

[Stu789]

Hello again,
I found the O ring (09280-55002), drive shaft seal (seems you need 2, 09282-24003), sub water tube bushing-trim tab end (17564-94500) and even a gasket for that end, but I can't locate the most importand part--the sub water tube gromet at the water pump end. Also, I seem to recollect that once I removed the heat shield I could pretty much get at that end of the sub water tube. Are you sure I have to remove the bearing cap, etc.?

[Solarman]

When you get in you will see the bearing cap is on too of the heat shield. You will have to pull it up to get heat shield out and put new grommet and heat shield back in place.

If you try to pull heat shield without pulling bearing cap, you'll have to buy a new heat shield.

Post back if any questions.

[Solarman]

Stu, you have the 2000 series motors. My motors are 1999. It is possible they changed designs in your motor? If yours are different i'm not aware of it. On both of my motors (I bought used) and after installing them on my boat, went through the normal, water pumps, gear oil, cleaning filters, etc. Only to find my initial run, went just like yours. Fine at idle to 2000 RPMs. Then they overheated. I thought a fluke, but when I saw steam in the tell tale, knew it wasn't.
Lucky for me, I found both seals (2 sets) for my bearing caps ( 1 oring seal, 1 seal for drive shaft, there is another oring at top of drive shaft, I replaced), and found both sub water grommets for the heat shield end, and one set of screws (4).

I reused both grommets on other end of sub water tube (none in stock here). I used all but one of the new screws, the previous mechanic/ person had buggared up the heads on three, and my impact driver had tough time removing. Once screws were out everything went smoothly, except the previous person installed my heat shields backwards, on both motors, which is why I had to replace the grommets after they did (without heat shield, both grommets were burnt and loose at tube-not sealing)

You will notice the improvement on your first run over 2k RPMs.

Good luck Sri, post back if any problems.

[tybee2]

Greetings, Solarman!

I, too, own a DT140 with what appears to be the exhaust leak into the water pump. the symptoms i have are the overheat and the telltale pees pretty good and then stops and then starts again. i've checked the head passages and those are good, no obstructions in the telltale passageways, i've replaced the thermostat and the water pump impeller. all look good so i'm down to the sub water pickup tube gaskets. or at least i think i am.
i have just enough mechanical skills to replace the thermostat and the waterpump.
replacing the o-rings and the drive shaft seal makes me a bit nervous so i guess i'll buy 4 o-rings and two of the drive shaft seals in case i hose those up.

from looking at this diagram: Fig. 45 - Gear Case - Suzuki DT 140 Parts Listings - 1986 to 2001

i assume the parts for the water pump end of that sub water pickup tube that form the gasket/grommet/shield are parts number

13 - exhaust seal rubber
14 - exhaust seal plate
19 - exhaust seal cover

and the parts for the other end of the sub water tube are:

16 - sub water tube gasket
17 - sub water tube bushing

yes?

those and the O ring (09280-55002) and the drive shaft seals (09282-24003) [of which i will buy duplicates for that "just in case" situation] should do me, yes?

any special tools needed? i have enough tools to be able to remove the foot but i'd hate to get knee deep in this and need something.

and, lastly, any tricks that you could impart to a non-mechanic outboard novice?

Thanks in advance,

Tybee

PS - how did Stu do in his repair? has he surfaced elsewhere to report success?

[Solarman]

Stu, in order to replace the sub water grommet you have to lift the heat shield up at least 1/2”, maybe a little more. The bearing cap sits on top of the heat shield, so that has to be lifted as well. You might experiment with lifting just high enough to turn the bearing cap 90°, or less to be able to access the heat shield and grommet, but if you do want to put the new oring and shaft seal on the bearing cap, it must be removed.

If you do decide to lift the cap, as soon as you can, push a clean rag into where the cap was, all the way around the drive shaft (leave the drive shaft in the hole). This will prevent anything falling into that hole, or moisture contaminating the gear oil (keep unit in upright position during this entire repair, and you do not need to drain gear oil).

Tybee, the only grommet that must be replaced is the sub water grommet. The heat shield and and cover are probably not damaged, but you are welcome to have on hand, if you can tale them back of not used.

The only reason I replaced the bearing cap oring, and seal wasn't because they were bad, but because buying my motors used, and finding my heat Shields on both of my motors put in backwards, told me not to trust the previous persons work. And I didn't wish to remove the lower unit another time because of water leaking through those seals, contaminating the me oil in the gear case. The price of all those parts was less than $30, each motor. The price of the synthetic gear oil, much more than those seals.

That webbing in the housings (going side to side, is not just there to strengthen the housing, it is also there to prevent the high pressure exhaust gases (usually the black sooty chamber) blowing back into the water chamber. If those webs are damaged by corrosion they also need to be repaired. Those surfaces need to mate together (do not need gaskets) when the lower unit is bolted back together.

Stu, I don't know what screws you have holding your bearing cap down, it is most important to use the proper bit in those screws, and not damage them. This is the only special tool needed, I use an impact screw driver with a large Phillips bit, but you won't know if you need an Allen socket or what till you get there.

Good luck. Post back of any problems.

[tybee2]

When you say "the only grommet that must be replaced is the sub water grommet", that is the piece in the diagram labeled

reference 3, p/n 55332-94510, description "Exhaust Seal Rubber"

yes?

the webbing around those parts just aft of the waterpump are corroded/damaged so I guess I'll be playing with some JB-Weld for a bit.

Thanks for all the advice. I'm sure i'll have more silly questions as this project moves forward. I'll order the parts today and as soon as they arrive, I'll drop the foot and begin the process.

Thanks again,

Tybee

[Solarman]

Yes, #13, and if available #17 in the pic of parts shown below.
I can not see the parts diagram at boats.net.
If your motor has #15 - sub water tube, then these are the seals for that tube.
The oring for the bearing cap, and the drive shaft seal for the bearing cap are shown on the water pump diagram.

Fig. 45 - Gear Case - Suzuki DT 140 Parts Listings - 1986 to 2001

Yes tybee, use a good aluminum epoxy to repair the webbing, clean the area well, so the epoxy holds good.

Post back if need to.

[tybee2]

Parts are on the way....

(finger crossed hoping i can get this done)

Tybee

[artdf175]

At what rpm level does the overheat problem occur?
My 175 was at idle At 1500 rpm+\- or greater the overheat went away as enough water was getting to powerhead to cool it down
There are a couple of places to look for water dumping into exhaust ports one easy to look at the other requires taking the power head off as the 2nd place is the water/exhaust jackets that run through the oil pan
The easy one to check --- big assumption the basic configuration on the 140 is similar to the 150/175's---
On the port side is a fresh water rinse plug --carefully remove that cover plate as the potential exists for the screws to break when trying to extract them
If the leak is here the leak is more than obvious
Art