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One engine still running hot

J

jeffsboat

Contributing Member
Background - twin 318s with closed loop cooling. Port engine runs 175F and starboard can get up to 200F. Back flushed the raw water path and found that all looked good from the heat exchanger back. I was not sure about the heat exchanger as it took more hose pressure to push water through. I was considering unhooking both hoses from the exchangers to the exhaust on both engines and see if the flow is different. Is there any other method of inspecting the flow throught he heat exchanger? I was able to run the port engine at 3400 rpm and the starboard at 3000 rpm and keep both at 175F.

I also feel that the starboard engine drive shaft is not alligned as well as the port. Is this an easy process to reallign a shaft? I am an engineer so I was going to use a dial indicator to set the shaft allignment.

Thanks,
Jeff
 
That might help, but I'd take a good look for air leaks before the raw water pump first. It doesn't take much of a leak to cook an engine.

Jeff
 
What kind of shaft seal do you have? Im working with the dripless right now but not familiar with the packing gland that much
 
I use teflon packing. Virtually trouble free, and if it fails the boat doesn't sink (unlike dripless shaft seals).

Jeff
 
Both the boot and the seal faces can fail, allowing a lot of water to enter. More common than you'd think.

Jeff
 
For shaft alignment, unbolt the shaft coupler with shaft from the tranny flange. Pull the coupler away from the flange and note if it springs to one direction. This could be an indication of how far out it is and which direction is needed to correct the issue. Check that the mating surfaces are clean and free from corrosion. Mate the coupler to the flange (do not bolt) and with a feeler gage, check for gaps between the flange and coupler. Shoot for no more than .003 gap all around. You may have to move the front or rear or both ends of the engine up or down and sideways to achieve this. When you think it’s right, rotate the flange and shaft 180 degrees and check the gaps again. If there is a difference or more of a gap on the opposite side than before, then your coupler or flange is warped.

Ideally before you do all this the boat is out of the water and you ensure the strut bearing is in good shape, that the shaft sits in there evenly, and that it is relatively close to centered when going through the hull. But the final alignment should always be done in the water after the boat has sat for a day.
 
Quick question on shaft allignment. Do I just loosen the bolts and let the shaft find it's own position, measure the gaps and then start making adjustments until the gaps are all even around the flange mating surface? Also, do I have to remove the shaft packing so the shaft floats free on the cutlas bearing?
Thanks,
Jeff
 
Its my opinion that you need to be centered in the stern tube to make a correct alignment. Its also my opinion that that if your not rubbing the stern tube in any seas except for a white squall! and you feel that the shaft will stay centered at the stern tube when you disconnect you can adjust motor/tranny mounts accordingly.On mine (Dripless rubber boot that floats in the stern tube)If I disconnect it will rest on the stern tube and mess me up I would then need to go under the boat and make sure I was centered in the stern tube with some shims and then mate the coupling faces to each other.

I wouldnt mess with it unless you can see bad alignment when you put it in gearand watch the rotation like the video I did. A major vibration i would think is a bent shaft or unbalance dirty shaft,Prop
 
I remove the bolts completely. This allows you to back the coupler away from the flange and inspect the the mating surfaces. Rust will throw off your reading. I don't like making adjustments to the engine with the surfaces mated. It is also the only way to rotate the coupler 180 deg after aligned to check for a warped coupler or flange. I like to measure again at every 90 deg rotation. I know it seems like a lengthy process and conditions can be tight at times, but I don't like revisiting the issue and doing it all over again after a sea trial.

No need to remove packing.
 
My heat exchanges (CAMP) have removable ends to clean them out. Sometimes seaweed gets in there......I haven't installed sea strainers yet. I also discovered several 3 inch oysters growing under the sea strainer underneath the boat when doing bottom paint one year. I had checked water flow by pulling off engine feed hoses and they both flowed about the same. Later that year I found the oysters growing under the slotted strainers/covers under the boat. The thru hulls were clear,but the oysters hiding under the cover must have impeded the water flow enough to make a difference. Sometimes there are strange answers to our problems.
 
If you have the v-drives ,I would take the plate off and clean that out then clean your Heat exchanger and blow out all the lines I found tons of metal flake which will clog a heat exchanger quick not to mention the sea water pump getting struck buy metal flakes

Thats a v-drive though
 
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