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David Thompson
Member
Username: kiwi_dave
Post Number: 19
Registered: 12-2007
| | Posted on Wednesday, May 07, 2008 - 12:23 am: | 
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Further to trying to get this bloody problem fixed.
Replaced Waterpump on my 1408430 78 140 hp Rude, after previously replacing thermostats (fused closed), to try and fix overheat buzzer issue when getting up on to the plane.
Previously was able to get on plane for only 5-10 seconds before buzzer went off. After replacing Tstats and water pump, planed for about 60-120secs before buzzer sounded. powered down for 2-3 mins and buzz stopped (prev had to pwr down and stop for 20 mins). Cruised around for 3-4 hrs doing 4-6 knots no prob, but when tried to plane, Buzz !!!.
Local service tech, advised to check water flow through 2 hoses from tstat to cylinders to check condition of deflectors. Water flow seemed very strong. I will be testing temps on both sides with laser temp gauge this weekend, so can any one tell me the min/max temp that will cause the horn to kick in.If anyone knows how to test/replace temp sensors, please let me know. Please any further suggestions would be greatly appreciated, as im running out of options.
anyone suggest |
Larry Jones
Member
Username: nowgrn4
Post Number: 4
Registered: 05-2008
| | Posted on Wednesday, May 07, 2008 - 08:38 am: |
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I had the same problem years ago on a V-4.Even after replacing the expanded deflectors the engine ran hot(I was taught by a good OMC mechanic that you should be able to momentarily touch the cylinder heads with the engine fully warmed up.It should be quite warm but not so hot that you think you burned yourself).The bypass valves supply the majority of water for cooling at WOT,not the thermostats.I cut off about 25% of the spring (behind the valves) and stretched and reshaped it to it's original length.The result was increased water flow through the valves.Problem solved.Also was this engine re-jetted to run at higher elevations?If so this lean/hot jetting at sea level could contribute to overheating.Hope this helps. |
jwbmarine
Senior Member
Username: jwbmarine
Post Number: 1440
Registered: 11-2005
| | Posted on Wednesday, May 07, 2008 - 09:35 am: |
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, so can any one tell me the min/max temp that will cause the horn to kick in.-> activates at 211 degrees...stops activating at 176.
This is THE most overhauled eng i have ever done and been around...ck your comp/pistons/cyl walls...and water delfectors in block,behind cyl head. |
David Thompson
Member
Username: kiwi_dave
Post Number: 20
Registered: 12-2007
| | Posted on Wednesday, May 07, 2008 - 04:52 pm: |
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Thanks Larry, I will try cutting down the springs a little, as you advised. Even after completely warmed up, still able to touch head/block with out a hell of a lot of discomfort ( but still couldnt leave the hand there).
However would this be masking another major issue ? |
David Thompson
Member
Username: kiwi_dave
Post Number: 21
Registered: 12-2007
| | Posted on Wednesday, May 07, 2008 - 05:01 pm: |
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Thanks JWB, my manual doesnt give any min max running temps for each or both sides.. Id just like to establish that both sides are running at normal operating temp, to establish if maybe I have a sensor problem on the port side. As I mentioned prev, the sensor wire on that side seems to move in and out of the plug in the head. I was advised that one side runs hotter then the other, are you able to tell me which ?. Thanks Dave |
Larry Jones
Member
Username: nowgrn4
Post Number: 5
Registered: 05-2008
| | Posted on Wednesday, May 07, 2008 - 06:39 pm: |
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Dave,turn on the key and wiggle the loose sending unit.If it goes to ground the buzzer will sound.Lets eliminate this variable. |
David Thompson
Member
Username: kiwi_dave
Post Number: 22
Registered: 12-2007
| | Posted on Thursday, May 08, 2008 - 04:49 pm: |
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Hi Larry, wiggled sensor with key on, no buzzer, however noticed on the weekend that when the buzzer sounded, I was able to wiggle the sensor wire which made the buzzer stop and start, what would you suggest next. Im going to test the temp this weekend with laser, to see what temp both sides (when buz sounds) and establish if running at normal operating temp or if in actual fact if one side is running hotter then other. I will also check compression over w/end.thanks for your help Dave |
Larry Jones
Member
Username: nowgrn4
Post Number: 7
Registered: 05-2008
| | Posted on Thursday, May 08, 2008 - 08:35 pm: |
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There is a sender for each cylinder bank.Compare temps with the pyrometer and if they are comparable then disconnect the push-pull connection to the suspect sender.If the buzzer stops then I suspect a faulty sender.Also check the plugs.A plug that looks a lot lighter than the rest indicates a lean condition/carburetor problem on that cylinder.These old 140's are very high performance engines and running lean can cause a catastrophic failure very quickly. |
David Thompson
Member
Username: kiwi_dave
Post Number: 23
Registered: 12-2007
| | Posted on Thursday, May 08, 2008 - 09:34 pm: |
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Thanks Larry, I believe the 2 banks operate at different temps, one side hotter then the other, would you know which is which?, What would be an acceptable variance be, between each side if the buzz activates at at 211 degrees...stops activating at 176.
With the sender units, are these push in, pull out, type install/uninstall?, or would the head or or outer head cover need to be removed to get at it. Re Plugs: As it happens, I checked the plugs when I got the bugger home, they seemed to be ok, slight oiling but nothing over the top. will also check compression today as per JWB. Would any one be able to tell me if I would be doing more harm then good running my rig around constantly at 4-7 knots ?. |
Larry Jones
Member
Username: nowgrn4
Post Number: 9
Registered: 05-2008
| | Posted on Thursday, May 08, 2008 - 10:00 pm: |
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All variables being constant.I couldn't imagine why one bank should run hotter than the other.If I remember correctly the senders are retained into the cylinder head water jacket covers.If you remove them be sure to replace the deflector's.I don't think running at trolling speed for extended periods will harm the engine in any way.I have always ran a temp gauge and have owned 3 V-4 John-Rudes and all have run cooler at planing speeds than at slow/trolling speed. |
Morten Ringvold
Senior Member
Username: haffiman37
Post Number: 2715
Registered: 04-2006
| | Posted on Thursday, May 08, 2008 - 10:25 pm: |
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At low rpm, below opening of pressure valves, the temp should be equel on both sides. At higher rpm, depending on opening pressure of release valves, pump capacity, restriction in water passages (deflectors?) etc there might be a smaller difference, but not significant. The switches are at the same release temp!.
When You changed the pump/impeller, how was the big rubber seal between exhaust and lower gear case?
In cases similar to what You describe I sometimes did the following:
Down gear case, attached a hose directly on to the water tube, blocked one of the outlet (rubber hose) from the heads at the time and flushed through each bank individually. Keep a bucket under the engine and collect the water coming out. It should take the same time to fill the bucket on each side If not -a restriction or faulty pressure valve. If You on top have the possibility to make a T-connection on the hose and hook in a manometer, You may get the opening pressure of the valves at the same time. This test might save You a lot of tearing down and parts change without knowing why! |
David Thompson
Member
Username: kiwi_dave
Post Number: 24
Registered: 12-2007
| | Posted on Friday, May 09, 2008 - 12:20 am: |
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Thanks Morten .... The rubber seal admittingly was a fairly loose fit, I thought of replacing but condition was better then reasonable. after cleaning and resealing 2-3 times (as I kept moving it when mating the water hose), it seemed to fit ok. My manual seemed a bit short of descriptive help as it did not suggest that the seal should be absolutly air tight ?. |
Morten Ringvold
Senior Member
Username: haffiman37
Post Number: 2716
Registered: 04-2006
| | Posted on Friday, May 09, 2008 - 12:35 am: |
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That seal must be close to 'press fit' or exhaust will leak into the water pump. |
David Thompson
Member
Username: kiwi_dave
Post Number: 25
Registered: 12-2007
| | Posted on Monday, May 12, 2008 - 12:59 am: |
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Could someone please advise what would happen if a 2 stroke was run for 5-10 mins with no oil in the mix, after it had been run for 1/2-1 hrs of 12 month old pre mixed fuel ??????? |
ikia
Visitor
| | Posted on Monday, May 12, 2008 - 05:06 am: |
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I am not sure what the oil does when mixed that long.When it condenses in the crankcase does it still have good lubricating properties???Running that long at idle without oil you may be lucky at full throttle it is a problem.Best to pull the bypass covers ( If motor has them ) and have a look at the pistons and rings.This again proves that most motors end up in the repair shop because of a mistake. |
David Thompson
Member
Username: kiwi_dave
Post Number: 26
Registered: 12-2007
| | Posted on Monday, May 19, 2008 - 08:53 pm: |
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Im about to pull the head on my port bank to check cylinders and check deflectors, but as per JWB or or advised, did a compression test first. I was a bit suprised with how low my numbers were especially after seeing numbers like 120-130 psi from other visitors to this site. My readings were 90-95 fisrt try,
and 80-85 all round (+/-2 psi). Is that too low ?. Also Ive recd the instruction from Joe Reeves or JWB re the replacing the deflectors(Thanks) , but are there any other heads up/ tips that will ensure it is a one time job, or will make it easier |
