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Volvo Penta AD 41 - outdrive

C

colinafloat

Member
Hi , I have two 1991 volvo penta's , one of which is overheating . She will sit all day at 10 knots but any more power & she will overheat . It is possible to achieve 25 knots but within 2 minutes the temp gauge begins to creep up towards 200 f.
I understand that it could be a water flow restriction in several area's .Sea water pump has been changed & looks fine as does the sea water filter . Outdrives are new to me & i do not think the outdrive has been serviced for some time .
Any advice enabling me to locate the problem area would be appreciated ?
Thank you
Colin
 
Does the temperature continue to rise above 200? Check both temp sensor and gauge and also temp warning sensor if there is one for accuracy. Check engine temp with with infrared gun. May be engine runs normally hot and if sensors or gauge has error engine isn't really overheating. Otherwise could be obstruction in raw water line. A burned out impeller can be the culprit. Check heat exchanger, riser, turbo, and exhaust horn check for rust and corrosion around fittings. Try flushing raw water system with "Salt-A-Way"
introduce it into intake hose. Good idea to permanently splice raw water intake with a hose and valve to flush on a regular basis.
Good luck.
 
Check water pickup hose on the outdrive, they can slip off or connecting neck elbow can crack (if plastic) to corrode (if aluminum). This hose sits directly below the bellows, on the outdrive front side.
 
stringer_bell said:
Check water pickup hose on the outdrive, they can slip off or connecting neck elbow can crack (if plastic) to corrode (if aluminum). This hose sits directly below the bellows, on the outdrive front side.
Click to expand...

Hi , thanks for the advise . I am suspicious of the outdrive / water feed to the engine . I have no history of the outdrive being maintained & i understand that the bellows should be replaced from time to time .
If the hose is loose or is cracked i would presume that air would gain entry to the cooling system ?

I will need to arrange for the boat to be lifted & inspect the outdrive .

Thanks again
Colin
 
aimee_lynn said:
Does the temperature continue to rise above 200? Check both temp sensor and gauge and also temp warning sensor if there is one for accuracy. Check engine temp with with infrared gun. May be engine runs normally hot and if sensors or gauge has error engine isn't really overheating. Otherwise could be obstruction in raw water line. A burned out impeller can be the culprit. Check heat exchanger, riser, turbo, and exhaust horn check for rust and corrosion around fittings. Try flushing raw water system with "Salt-A-Way"
introduce it into intake hose. Good idea to permanently splice raw water intake with a hose and valve to flush on a regular basis.
Good luck.
Click to expand...

Hi & thank you for your reply .

THE ALARM ACTIVATES AT195 & I THEN REDUCE REVS WHEREBY THE ENGINE TEMP FALLS TO 175 WITHIN 30 SECONDS & WILL REMAIN THERE UNLESS I INCREASE TO SPEEDS ABOVE 10 KNOTS .
I DO FOLLOW YOU & NEED TO SWITCH CABLES ON THE TEMPERATURE GAUGES & MONITOR THE ENGINE MORE CLOSELY AT HIGHER REVS.
i WILL ALSO CHECK TEMPERATURE OF SEA WATER COOLING CIRCUIT LOCALLY & COMPARE WITH THE OTHER ENGINE .
YES - DESCALING WOULD CERTAINLY BE BENEFICIAL .

Thanks again
Colin
 
Thank you .

I need to lift the boat for anyifouling & will need to have the outdrives serviced & the water inlet checked .
I can switch cables to check accuracy of temp gauges & alarms .
I can also monitor engine directly & compare with the other engine .
Is there likely to be any engine damage ? How can i test for faulty head gasket ?
I did loose a small amount of cooling water via the header cap at the higher temperatures but can see no bubbling when compared with other engine .
 
Thanks for advise . I will look into actual temps & sea water cooling circuit .
I also seem to be loosing a small amount of water from the heat exchanger lid .
Maybe a head gasket ?
I need to lift the boat out & will have the outdrive serviced & water inlet checked
Fingers crossed .
Thank you
Colin
 
Hi Colin.... A knowledgable member (Morton) suggested the inside elbow of the transom shief be checked. Earlier 41 models like my B have a bronze valve, and the latest model P has the plain plastic elbow. It is a good idea to check this and if it is the valve version make sure it is not clogged. If it is in good shape, it can be used in conjunction with the T setup suggested earlier. This is what I have since it really helps with winter antifreeze flush of the raw water side of my cooling system. It is essential there are no leaks on the pickup side of the raw water pump. After that it is just a no harm leak. If U have good going in... and U check there are no blockages going out. then U have to read Morton's advice on tracing the cooling system with a heat gun to find the blockage you HAVE missed. Removing the outdrive seems a waste as the only parts are the elbow and rubber hose. Both of these are replaceable I think and easy to view with the drive installed.
 
Colin, I experinced a condition wherein the thermostat on the re-circulating water side did not open fully. It caused over heating. Hope this is helpful.

pv
 
skiss said:
Hi Colin.... A knowledgable member (Morton) suggested the inside elbow of the transom shief be checked. Earlier 41 models like my B have a bronze valve, and the latest model P has the plain plastic elbow. It is a good idea to check this and if it is the valve version make sure it is not clogged. If it is in good shape, it can be used in conjunction with the T setup suggested earlier. This is what I have since it really helps with winter antifreeze flush of the raw water side of my cooling system. It is essential there are no leaks on the pickup side of the raw water pump. After that it is just a no harm leak. If U have good going in... and U check there are no blockages going out. then U have to read Morton's advice on tracing the cooling system with a heat gun to find the blockage you HAVE missed. Removing the outdrive seems a waste as the only parts are the elbow and rubber hose. Both of these are replaceable I think and easy to view with the drive installed.
Click to expand...

I need to lift the boat to antifoul & inspect outdrives . I will certainly check the sea water inlet & bare in mind what you have suggested . The outdrive has not been serviced for some time & whilst ashore i wish to change anodes & bellows . I have not much experience of outdrives , would you know if it is difficult to change the bellows ? I am an x RN engineer but have no experience of outdrives & am not sure if any special tools are required ?
Thank you for your help thus far .
Colin
 
pvbud said:
Colin, I experinced a condition wherein the thermostat on the re-circulating water side did not open fully. It caused over heating. Hope this is helpful.

pv
Click to expand...


Hi ,

Thanks for your advise . I need to lift the boat to antifoul & service outrives & check sea water inlet . Once back in the water i will check the thermostat .

Thank you
Colin
 
stringer_bell said:
Check water pickup hose on the outdrive, they can slip off or connecting neck elbow can crack (if plastic) to corrode (if aluminum). This hose sits directly below the bellows, on the outdrive front side.
Click to expand...


Spot on - thank you
The hose had come adrift completely as the allow conection had vanished due to electrolices. Have now replaced connection & hose seemed ok .

Any luck that has cure the problem

Thanks again
 
stringer_bell said:
Check water pickup hose on the outdrive, they can slip off or connecting neck elbow can crack (if plastic) to corrode (if aluminum). This hose sits directly below the bellows, on the outdrive front side.
Click to expand...
Many thanks . Boat now out of water & the connection had vanished allowing the hose to wander ! It was a aluminum & has now been replaced .

Thanks once again
Colin
 
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