volvo 9hp overheating

[hudsonxx]

Having just bought a boat with this volvo single cylinder engine i find that on aything above half throttle the over temperature alarm sounds. Is this a common finding and is there a solution.

sadler 26

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[frilaens]

Is this the 2001 and seawater cooled?
Overheated mine by...

Faulty thermostat and defective alarm - replaced
Choked exhaust elbow - dipped in acid to remove scale (inlet hole had a 50% reduced diameter!)

Dived under to check the prop, checked impeller, filter and replaced pipes in an effort to fix the above. Will try descaling the motor sometime with radiator treatment as it was fairly scaled up inside when the head was off for skimming. If I try draining the cooling water through the drain plug, it is often blocked by small scale/sand particles and needs a good poke with a screwdriver to get it going!


Useful links
Volvo Penta user group
http://www.motoren.ath.cx/

2003 Parts catalogue
http://www.westerly-owners.co.uk/html/volvo_gearbox_splines.html

Andy

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[frilaens]

...and I bored out the hole in the pipe that goes through the head after a tip on this excellent forum. The original was 4mm and the poster recommended 6mm. I eventually used 5. The poster said this was a known problem.

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Andy

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[mldpt]

If this is the 2001 and is fresh water cooled you will have a small pipe leading from the thermostat housing. this pipe goes back to the header tank, remove this pipe from the thermostat end and make sure the hole in the brass pipe from it is clean it is about 2mm. replace the pipe and all could be cured. I spent months with this overheating problem on my 2003 back in 1996 once the breather hole was cleaned water could once again circulate the head when blocked it creates an air lock in the head and prevents circulation hence over heat alarm I hope this is your problem as its so easy to cure.
Regards Mike

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[philwebb]

Pull out the impeller and have a close look at it. On some types of
impeller the brass bush in the middle comes adrift from the rubber.
This is not easy to detect as it works OK at low revs then slips
at higher revs. If you have just bought the boat changing the impeller
(and getting a spare one) is probably a good idea anyway.

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[hudsonxx]

many thanks to all, I have already replaced the impeller and the engine is raw water cooled 2001. Water freely exits the stern and increases flow with revs. I will act on present advice and report again of my findings, I am not at the boat for three weeks so any further advice or suggestions will be taken on board, literally!

Is it usual for this engine to take about 30 seconds to start from cold? Can a preheater or glow plug be fitted?



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[frilaens]

For the start there is a "cold start procedure" which is

Dis-engage the gear and put the throttle at 80%
Pull the stop (I hold it for a couple of seconds but I don't think this is necessary)
Turn the key

In my experience this didn't help until I had the valves re-set and improved the compression. Mine used a similar time to fire. As I don't have a rev counter yet I am not really sure what 80% is and I am still experimenting. Sometimes she will start from cold after a couple of turns, sometimes with less than 50%, other times she turns for 5-10 seconds before catching, or catches if I push the gas up to 100% just for a moment.

Slow starting is maybe a symptom of poor compression; try a compression test.

Andy

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[jleaworthy]

I think your problem is most likely to be scaling in the brass cooling tube which passes through the cylinder head. To get at this tube you will need to remove the hose fitting at the front of the head which receives water from the water pump and also the hose fitting at the back of the head leading to the exhaust elbow - just a single set bolt on each. You then need to drive out the brass tube with a suitable drift. It has to come out at the back. As it is coming out look carefully at the position of the holes - the tube is a bit like a short penny whistle - as it will need to go back the same way. Descale the tube. I also drilled out the holes on my 2002 to about 6mm. Overheating on mine was cured. Good luck.

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[hudsonxx]

many thanks, can you tell me if this can be done in situ or does the head need to come off, also as I will need to be taking tools out to the boat, is there anything specific required to knock the tube out?

thanks once more for your input.


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[frilaens]

The tube can be removed in situ; I used a (if I remember correctly) 10mm socket on a 1/4" extension bar to push it out and a 12mm to put it back in. The 12mm fits nicely inside the rubber seal. It might be a good idea to have a new seal. I used a slowly rotating wood drill bit (8 or 9 mm??) inside the pipe to remove the worst of the scale build up. As the previous poster said; pay it inside attention to the orientation of the holes and let me know! I am trying to find out which way the single hole on the 2001 should face. The workshop manual I have is for the 2000 series, i.e. with multiple holes, and the example says 6 and 8 o'clock when looking from the gearbox.

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[EdEssery]

On a Volvo 2001, the hole should be at the six o'clock position when looking at the pipe from the gearbox end - i.e. pointing downwards.

I just cleaned the pipes on both my engines and the position of the hole was the same on both. I practiced the technique on the old engine I removed 'cos of low compression first before trying the new (to me) replacement Volvo 2001 which has been having overheat alarms after about an hour's running. I found the hole in the pipe in this engine was completely blocked with scale.

I cleaned the pipe up with kettle de-scaler and then drilled the hole out from 4mm to 6mm. Hopefully this will have cured the problem.

We shall see over the next few weeks.

Ed

 

[Nina Lucia]

how did you remove that pipe?
I have same problem with my volvo 2001?
Many Thanks
Ivan
ivan.n@ntlworld.com

 

[Ben_e_Toe]

I would agree with all the above. Took advice from several excellent posts and:
1) De-scaled exhaust elbow with acid
2) Removed pipe through the head, cleaned and drilled out to 5mm
3) Replaced thermostat
4) Drilled-out coolant drain hole so that I can properly drain out deposits (and bits of decomposed inhibitor anode)

Runs very well, no overheating problems!

Just one though, how can you test that the water temperature alarm-sender actually works? Or is it suffice to say it works if the light comes on before start?

 

[Nina Lucia]

I have same problem ( overheating)with my volvo 2001sail drive on GK24, would you mind teliling me how to drain engine and remove that pipe, please?
Many Thanks
Best regards
Ivan
ivan.n@ntlworld.com

 

[Ben_e_Toe]

Ivan,

If you turn off the inlet seacock, then find the drain valve on the starboard side of the engine. It's about two thirds of the way down and quite well hidden. You will need a long socket to loosen the nozzle (13mm I think) and may find that it is blocked with sediment stopping it from draining. If so just fully remove the nozzle and have a good poke around with a screwdriver until the engine starts to drain - there's nothing on the inside that can be damaged by reasonable use of a screwdriver.

Once drained, you need to remove the pipes from the front and rear of the head-gasket pipe. One is a pre-formed copper tube from the exhaust (at the rear) and the other leads from the impellor pump. The head-gasket pipe isn't immediately obvious, but if you get a 10mm socket on a long extension (10 cm) and push it into the hole at the front of the engine, a pipe will appear at the rear of the head! The pipe can then be removed, de-scaled and re-drilled to 5mm. Refitting is the reverse, although it's worth getting some new seals of the pipes (they should only cost pennies) before re-fitting. The key thing is to ensure that the hole in the pipe points down when re-fitting.

See 'frilaens' post above for more detail. Hope this helps!

 

[Nina Lucia]

Thank you very much, I will do my best, to push that copper pipe trough the engine. Do I have to drain engine before it?

 

[Ben_e_Toe]

Yes, it's a quick job to do, although you might want to put a length of pipe from the bleed fitting so that you can collect the water in a bucket. It's well worth finding the bleed screw, for quick draining etc anyway - you may well find it blocked with salty deposits (just 'drill' themnm out with a small screwdriver.

We keep our boat in a fresh water bay, the bleed is well greased and easy to use, so in the depths of winter I can quickly drain off the engine if a severe frost is forecast!

 

[Nina Lucia]

Ben, I manage to fix copper pipe, but not to bleed the engine. The bleeding screw is fine but looks like engine is full of stuff sand and muck so after 2 hours of pocking with screw driver and cleaning it was still block!
But engine at list not overheating any longer.
Maybe if I take those metal cocks of and try to unblock that from other angles...
Many thanks for your help, now at least I can do sailing!
Ivan
ivan.n@ntlworld.com