Suzuki DT30 still overheating at idle Help!!! (more photos)

[boatster]

I am almost at my wits end here. My motor is clearly overheating at idle. I take the thermostat cover off and it runs ok. The water comes pouring out. I put the thermo cover back on WITH a new thermostat and it pees but still gets very hot. The heat gradually rises and I shut it off before something gets destroyed. The water coming out the pee stream is 50 degrees Celsius. I replaced the impeller, wear plate, and gasket. What is going on??? I replaced the under powerhead gasket, the exhaust gasket and sanded flat the head and block. I have no clue what I'm missing here. Can someone please help??? Anyone know what might be going on? If you need to see photos or a video you can go to my other thread. Thank you.....<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=30;t=004342

 

[tothundr]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

I haven't read all of your other posts but I know SOME motors have rubber water diverters in the water jacket to route the water through the motor. I dont see any in the pic but I also dont know the water route. My 115 Johnson had I belive 2 in each side. If the diverters are missing, the water dosen"t flow through the water jacket properly causing overheating. Maybe someone else will know if your motor even has them. Also looks like some scaling in the water jacket, my jet ski was overheating because of restricted water flow, it drove me crazy for months, the problem was a flake of corrousion (I know that not spelled right but it's not coming to me) was hung in the discharge fitting and restricting the water flow just enough to overheat at high speeds.

 

[jleus]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

Did you stop the exhaust entering the water jacket?

 

[boatster]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

Tothundr,<br /> I don't think its a diverter but thanks for the suggestion.<br /><br />Hi jleus,<br /><br />thanks for following up on my progress. YOu know I didn't realize how particular the suzuki manual was on the cylinder head and block mating tolerances. It has to be within 0.03 mm or .0012 inches of tolerance flatness on a straight edge for both faces. I don't think mine are even close to that tolerance after I looked at my feeler gauge at .038 mm. THAT is paper thin. I think I'm going to have to take the head and block to a shop and have them take off a hair using a mill or whatever to get those tolerances back. The previous owner barely used this motor but also never tightened the head bolts down. I hypothesize that it got so loose that it allowed the block & head to warp significantly. I'm going to have to take it all apart again and have a look see. So in short to your question, no I haven't prevented the exhaust from entering my water jacket. But I've narrowed it down to a warped head/block surface mating. I'm going to get it machined. What do you think? SHould I sand it on plate glass or should I take it to a shop? <br /><br />Thanks again.<br /><br />Adam

 

[bigbrownbuku]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

just machine the head, the block rarely warps to the point of machinig.

 

[jleus]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

I would try to work it out with sandpaper on glass first. I had my head milled for more compresion, but was succesful on the block on my own. I had the best luck getting a piece of double strength cut to about the same size as the paper and glued the paper to the glass. Moved the glass not the block while sanding. Spray adhesive worked best and remained "flat" between the glass and paper. The head is light eneogh to move on the paper. Your succes on either side will depend on how far they are out. That thing must have gotten bad hot at some point.

 

[boatster]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

Well I just used 400 grit with spray adhesive on plate glass. I sanded the head and the block. I used a new head gasket, put everything back together and no luck. It runs a little better but it still eventually gets hot and exhaust still comes out the thermostat cover. I'm going to disassemble the head again and inspect it carefully. I might like to add that I used a .038 feeler gauge to check the tolerances and it all seemed well within spec. I can't imagine that much exhaust can escape through the head. I'm a few steps away from chucking this motor. Too bad, I've spent over $600 into this darn thing....

 

[jleus]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

Certainly puzzeling. Wish I was closer to you....I would really like to see this biatch. I know from experience and the popularity of the 25/30 three cylinder Suzuki in my area that these are very durable motors. There is a hole somewhere in yours and there is not many places for one to be, short of a crack.<br /><br />Not trying to be funny but I sure would like to talk about buying some pieces off of it before you throw it out!!!

 

[boatster]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

Do you think that enough compression could be leaking past the head gasket to cause the water to not flow and cool the block? My theory would be, the compression leak into the head is enough to put backpressure on the water, thus allowing the exhaust from the midcase housing to invade and exhaust to start flowing out the thermo cover. If you take off your thermo cover while running does exhaust come out?<br /><br />Also I don't think the block could be cracked since the piston walls for the most part are perfectly smooth. WOuldn't the piston walls be scored to hell first?<br /><br />And, how high of a tolerance do you believe the cylinder head and block surfaces should be to be acceptable? The manual says 0.03 mm. That is super fine. Does this corroborate with your experience? Do you think I should now just get the head machined flat?<br /><br />Lastly, how strong should the pee stream be?<br /><br />Many questions, so confused.<br />THanks again.<br /><br />Adam<br /><br />Here are photos of the head and block before my last reassembly. You can see I sanded them down on glass using 400 grit.<br /><br />

<br />

 

[jleus]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

The "dirty" spots on the block that you have highlighted don't neccessarily mean water leakage but you certainly did not touch them with the sandpaper. I worked mine until those were mostly gone. Still seems odd that with a fresh gasket it would leak. As to tolerance...I work both block and head on mine until I was certain by the marks from sanding that all surfaces were being contacted.<br /><br />Your video appeared to be while running on the hose. I don't see how exhaust would go anywhere but out the prop with no back pressure from being in the water. I get confused about your first question above. Yes if the head gasket is leaking it will displace water in the water jacket (been there). I don't think exhaust that has made it past the base plate into the mid is coming back into the powerhead if there is no back pressure from the foot NOT being in the water.<br /><br />I see from looking at the pictures of the block that you changed the gasket closest to the block on the exhaust cover but the gasket between the two plates appears to have the original paint on its edges. I would look between the two plates. I also "decked" the mating surfaces on both exhaust plates....the side of the inner plate with the extensions into the exhaust was basically just cleaned up well. A crack in that inner plate would not be super evident on the dirty side of the plate.<br /><br />Man I don't know otherwise. In your cleaning of the block before these pictures did you clean off the the piston tops, that #3 hole sure is shiny.

 

[boatster]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

jleus, I am going to give this one more shot. One more gasket to purchase. This time around I'm going to sand all surfaces till all surfaces are shiny. On my last attempt I did leave alot of untouched material on the block mainly because I had already hit the piston sleaves of all three already. I thought that was the most critical on that part. As well I took my 0.038 feeler gauge & straight edge and everything looked pretty straight. <br /><br />In my video the motor was in the bucket. I know the muffs don't always work. So backpressure is definitely there. As a matter of fact I'm going to test the motor today without the lower unit in water and a hose directly connected to the inlet tube. I want to see if exhaust is still coming out of the thermo cover when there is no backpressure. <br /><br />I didn't think to check that secondary exhaust plate. When I purchased this motor I was going for replacing the gaskets that had failed (ie you can tell the saltwater was getting out head/inner exhaust gasket). I will consider peeling apart the two exhaust plates and looking at their surfaces. But doesn't only the face of the inner gasket seal from the exhaust?<br /><br />With regards to cylinder #3 and the rest of they cylinders, I did scrape off all the carbon deposits on the crown of each piston. However the engine has hardly been used so even the piston walls are fairly clean and smooth. This is why I don't think the block could be cracked.<br /><br />On a whole, I can tell the motor is remaining cooler longer than before I had resurfaced the head/block. So I believe I am working in the right direction. Now I can see a stronger pee stream and the pee only starts to flutter when the thermostat opens up. But by the way the pee stream flutters you can tell that its getting batted around by the exhaust still. I should document this before my next tear down.<br /><br />Thanks again for your help/encouragement.<br /><br />Adam

 

[jleus]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

Yes the inner gasket alone seals the exhaust from the water passage at the holes through the inner plate into the jacket formed by the two plates. Even the way the block looks in the picture above I would think a new head gasket would seal. May seal better with a more even crush on all the metal there but still seal. The amount of exhaust exiting the thermostat hole would indicate a very evident gasket leak.<br /><br />I keep going back to the exhaust cover in my mind. That inner plate appears to me to have an interesting joining of formed and cast metal between the extensions into the exhaust path and the plate. <br /><br />If I remember the cooling water path correctly, I think it goes through that exhaust chest jacket first then the powerhead around the cylinders and to the thermostat (waiting for it to open to enter the area between the head and the head cover. Just seemed like water and exhaust was flowing in the same direction in the video and there was alot of exhaust to me, rather than exhaust bubbling back up the filled water jacket around the cylinders.<br /><br />IF maybe that inner exhaust cover is broken in some way the building heat flex's that formed piece away from the cast plate and there is a major leak into the water jacket. There should be some evidence of two stroke soot in between those two plates if the leak is there.<br /><br />Again, far flung ideas.....if that head is leaking with a properly tourqed head and a new gasket I would be suprised.

 

[boatster]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

Jleus,<br /><br />what kind of symptoms were you getting when your head gasket was leaking?

 

[jleus]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

It was #2, it actually dislodged about an 1/4 inch section of the crush ring. Thats why I sanded my block down well as I felt that there was little clamping effect other than right at the sleeve. Dead cylinder performance and steam exiting the pisser and small water/exhaust dump under the powerhead. Cranking compresion about 20 pounds. I still say that much exhaust leaking past something would be very evident at the point of the leak when disassembling. I don't see any soot in the block or the head in your pictures above. It doesn't take long to build up eneogh to see, hold your hand over the prop hub for about 30 seconds while running, that is what you should see at the leak. No steam either, to me that leak is away from the head.

 

[boatster]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

jleus,<br /><br />here is a photo of the head before I sanded it down. What might that tell you? To be honest I can agree with you that all that exhaust isn't coming from the head. You know one thing else is there is a less than an ounce of water that builds up at the bottom of the motor (where driveshaft inputs) that falls out when I remove the lower powerhead mount plate. Also last time I removed the head gasket there was a little bit of water/oil sludge on the wall of piston #2. Do you think if I'm getting so blow back from the headgasket that this could be causing enough back pressure to allow exhaust to come in from the midhousing? Like I said my motor is always tested in a bucket of water so the exhaust isn't coming out of the prop.<br />

 

[jleus]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

I don't see your problem being at the head. That level of leaking is not showing there. I also do not believe exhaust is coming back in from the mid. A hole that size would let the water out as easily, seems to me. <br /><br />The powerhead base is part of the water jacket. There is a sacrificial anode screwed to the bottom of the block in that part of the jacket, triangle shaped piece.<br /><br />I will bet you that oil/water/sludge was nearer the exhaust port.....may have run to the bottom of the cylinder....but left a trail from the exhaust port (there is just one). There is something wrong in those exhaust cover plates. My guess is the inner one. Did you find soot or the sludge between the covers?

 

[boatster]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

jleus I haven't checked the exhaust port side. I'm going to investigate that next. I'll put off pulling the head, as you may be right, the heads might be fine. I'm going to pick up a leak down tester to verify this. <br />I'll have to lift the powerhead off of the midsection to get all of the exhaust bolts off. I'll then split both exhaust covers apart as well as check the warpage on the block and exhaust cover. Everytime I've taken the exhaust cover off I haven't seen much evidence by way of sludge, oil leaking into the water jacket though but I'm going to check more carefully this time.<br /><br />BTW I ran the motor with a hose stuck to the water tube and the motor runs cool and of course pees strong. I also took off the thermo cover and no exhaust is not coming out of the thermo cover. So this really points to the midsection back pressure coming back through the main water outlet under the powerhead. This sure is like chasing a ghost.<br /><br />EDIT: I meant, I took the lower unit off and hooked a hose to the water tube thats supposed to go to the water pump.

 

[boatster]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

You know I'm thinking I want to plug some of those little purge holes under the powerhead. What do you think might be adversely effected by doing that? What purpose do they serve anyways?

 

[jafa]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

I'm not sure that yor dt30 leg is the same as my dt40 but there is an exhaust release plate located at the top of the leg, kinda reminds me of a grater. I get pressure out of there immediatly but do not get any water flow for a minute or so, running on muffs.It does "look like" you could put it on backwards and block the exhaust vent. I'm only looking at my parts breakdown. I dont want to sound sarcastic but I assume you have checked the exhaust is not blocked or a lump of rag in the prop hub/gearbox. If your running it in a bucket can you feel how much pressure is being pushed out of the hub ?

 

[boatster]

Re: Suzuki DT30 still overheating at idle Help!!! (more photos)

rockhopper,<br /><br />no rags, no blockages that I can see. When the motor is idling in the bucket it is not pushing exhaust out the propeller shaft, only the exhaust port in the back. When I rev it up then it starts to pump exhaust out the prop shaft. Clearly exhaust is getting in from back pressure now that I think of it. Exactly what is causing this backpressure to overcome the water flow is whats evading me. I've replaced the impeller, lower impeller plate and gasket. The one thing I haven't yet replaced is the impeller housing oil seal. Might that be letting alot of water slip out the system? I might have to check that out as well although the seal still looks good.