Warning alarm...low oil light on...but plenty of oil

[mzmanley]

Comments and guideance greatly appreciated.<br /><br />"The Patient": Recently replaced the water pump on a '86 Yam 200hp. I've had this boat for just over a year. This motor appears to have been well maintained or seen little use - very clean. It has run well for the past year and I'm getting familiar with the maintance issues, etc. Local mechanic check it out when I purchase it and compression was at spec and balanced with all cyl.<br /><br />Symptoms: Recently after replacing the water pump within 1 hr of running the engine warning alarm sounded. The low oil indicator light was lite up. Just prior to the alarm sounding for the first time the motor was having trouble exceeding 4200 rpm. Alarm stopped with key in forward positoin after 15 min. and then came in at low speed. Tried to rev. out the motor again and the alarm sounded again. All this time the jet of water from dicharge was very strong. Both oil tanks are full.<br /><br />I intend to try the thermostats and the oil level sending system, floats, etc. One individual I spoke to mentioned a filter in the base of the remote (engine) oil tank may be restricted.<br /><br />Last issue - Is it good preventative maintenance to pull heads and clean cooling jackets on this age of motor?<br /><br />Thanks for any help provided.

 

[mrn714]

Re: Warning alarm...low oil light on...but plenty of oil

You need to pull the oil tanks and clean them out. Clean the intak tube and lines. You must have a blockage in the lines. The oil sensor is being restructed as if it is getting air, not oil. The thermostat should be replaced when the pump is replaced. At least cleaned and service it. <br /><br />IF you have the carbs off, clean everything you can get gas or pressured air on.

 

[mzmanley]

Re: Warning alarm...low oil light on...but plenty of oil

Thanks for the feedback Thom...<br /><br />I will replace the thermostats and clean the tanks as recommended and report back. Can you shed some light on the cooling jackets.<br /><br />A general question regarding the cooling jackets on older motors (older V block Yams) - is there a good probability that some part of the cooling jacket is restricted with corrosion, etc. and is creating a local hot spot on cylinder walls. If so is it recommended to remove the heads and inspect the cooling passages? Thx again...Thom

 

[jim dozier]

Re: Warning alarm...low oil light on...but plenty of oil

Regarding cleaning the water jackets. I wouldn't do it unless you were having overheating problems or some other problem requiring removal of the head. If you were having overheating problems, then I would, but not before dealing with the more common things like impellers, thermostats, etc.

 

[mzmanley]

Re: Warning alarm...low oil light on...but plenty of oil

The thermostats and oil tanks will be attended to this weekend. I'll post the results.<br /><br />Appreciate the feedback!

 

[seahorse5]

Re: Warning alarm...low oil light on...but plenty of oil

This might help explain the oil transfer and alarm system.<br /><br /> http://www.bassandwalleyeboats.com/site_page_897/article_page_98.html

 

[mzmanley]

Re: Warning alarm...low oil light on...but plenty of oil

Thanks for the link Seahorse. I'll tackle the troubleshooting this weekend and post the results. Thanks to all

 

[mzmanley]

Re: Warning alarm...low oil light on...but plenty of oil

Problem diagnoised! - While replacing the thermostats I noticed the T-stat on the bank of cylinders that was running hot was defective (it was not opening). The overheat stressed an already weak head gasket. I noticed that the motor did not smoke when first fired up. I pulled the plugs and found water (drops) in two of the clynders. The head was pulled and sure enough two cylinders were sucking water. The crank has since become very tight (its effectively seized). Time for a rebuild or new powerhead time not sure.<br /><br />It appears that the reason the alarm was triggered after the T-stat was replaced was that the compression and steam pressure was leaking into the water jacket and the the water pump could not circulate water through this bank of cylinders.<br /><br />FYI - It may be advisable that on older motors (or neglected motors) an alarm maybe the result of a failed head gasket. This situation needs to be addressed immediately so water introduced into the motor does not cause corrosion and result in a frozen motor. By the way this motor looked very good from the outside but the head gasket was in very poor condition. It maybe a good idea to reseal the heads once a year ($100 in gaskets, etc.). This was a '89 motor but it was rebuilt so the head gaskets may have been replaced within the past 5 years or so.