I'm running-in my B20 engine, this time only the rings need bedding in since the cylinders have been de-glazed. I have driven 400 miles now on special running-in oil. When should I change to normal 20/50 Oil ? The engine is running really well although I have not gone over 3500 rpm as yet.

Although the radiator was upgraded some time ago, my 4-blade mechanical cooling fan is not very efficient, a more efficient cooling fan is the 5-blade plastic fan. I haven't been able to locate one in NZ, although they are available from www.volvoworld.com. In the meantime I have installed an electric (blowing) cooling fan, in front of the radiator, just in case I need it as a back-up. I have wired it from an existing fuse with an on-off switch under the dashboard, a simple manual control. The water temperature needle moves to the hot area just after the engine is switched off (no forced circulation when engine and thus water pump is switched off) At a later stage I may control the electric fan by a thermostat and delayed switch off after shutting down the engine. The electric fan came off a Nissan Exa, it's a very compact, fast revving and noisy, 11" fan and installation was very simple by using the existing mounting brackets, drilling 3 holes was all that was required. I only want to use it as an auxiliary fan, not to replace the mecahnical fan.

Jim Hekker
http://www.ccar.co.nz/volvo/updates.html

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Nice fan if it works for you

Unless it is REALLY hot there I would recommend a lighter oil.
10-40 is good for a worn engine but with new rings and good bearings
I would think 10-30 would be better. Heavier oil requires more power to
circulate and also to turn bearings in, so unless you need it, you are not
doing yourself any favors. Lubrication of lighter oils is just as good,
maybe better.
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George Downs Bartlesville, Oklahoma

The mechanical fan only does something useful at a rest or very low speeds. The rest of the time the motion of the car provides ample air flow. That being the case the mechanical fan doesn't work well when it needs to (idling at rest) and at high rpms it is doing a lot of work (draining HP) when it doesn't need to. They tried to mitigate this in later cars with the viscous clutches that would let the fan slip but the fact remains it is 'on' all the time when it rarely needs to be.

My 544 with the mechanical fan would just plain overheat if it sat and idled for a while on an even faintly warm day. And if I ever got stuck in stop and go traffic I had to turn the heater on. The puny mechanical fan just didn't wave enough air around at low engine speeds. Plus - if I shut it off after some quick driving it would occasionally boil over after sitting for a few minutes.

I put a 15 inch electric fan on, removed the mechanical fan and have been VERY pleased with the results. Now if it sits and idles for extended periods the fan just comes on for 30 seconds every 5 or 6 minutes. Once in a blue moon it will kick on in slow traffic. And on warm days it will cycle once or twice after shut-off and prevents boilovers.

Thanks John, that sounds like a good solution, what type of fan are you using, a pusher ? I think the 544 radiators are larger and I don't think there is space for a 15" fan on a 122 radiator, but I will remove the mechanical fan and do some tests with my 11" electric fan only.

The problem I think is that the hot air is trapped in the engine bay when the car is not moving and the fan is only ticking over at low speed and unable to blow the hot air under the car. I haven't had any boil overs after shutt-off but don't like to see the temp gauge needle going in the hot area.

Jim Hekker

Yes - I put the fan in front of the radiator pushing air through - there isn't a lot of clearance between the engine and radiator even with the fan taken off the water pump. The 544 radiator is nice and square and the 15 inch fan reaches to all four sides. I even had to trim a little metal out from the top section of the nose to get it to fit. It is probably a little bit of overkill - your 11 inch fan should probably provide enough air movement.

Boilover occurs when the engine goes from working hard straight to being shut off. An example would be coming off the highway right into a gas station. The block and cylinder has a lot of heat energy still in it but once the engine is shut off the coolant doesn't circulate much - so localized pockets can start boiling. This isn't much of a problem with an expansion tank but old cars just have overflow tubes aimed at the ground. The mild boiling pushes a little coolant out, eventually lowering your coolant level.

As a side note - I've noticed my VR6 equipped VW Jetta has a small elctric coolant pump in addition to a belt powered mechanical one. This mostly seems to run when the engine is cold - not sure what function it is serving other than to ciculate coolant around the block and head when the radiator is shut off by the thermostat. Volvo's do this (at least on B18/20 engines) with a dual function thermostat. When cold they not only shut off flow to the radiator but open a bypass vent which allows the water pump to circulate coolant in a loop through the head and block.

Where do you place the thermostat for the fan?

I've got a 740 fan on my 140 as the only fan and it seems to run at the wrong times. I've got the thermostat on the top radiator hose and set it so it doesn't turn on when the engine thermostat first opens but so it triggers just a few degrees higher.

Also the fan seems to produce a lot of backpressure against the radiator and I was wondering if any of you have this problem.

I know mine isn't a 120, but you all seem to know more about running electric primary cooling fans on road cars than I've found elsewhere.

Thanks!
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Alex Shevlin (Sydney): '72 144S, '81 244GLE, '81 244GL, '01 V70XC

Hi Alex,
I have installed the additional electric cooling fan in front of the radiator only as an "emergency" fan. The engine is running fine at normal temperature at the moment when driving the car, however the temperature creeps up a little at traffic lights, but as soon as I touch the accelerator and the water pump increases the flow, the temperature drops immediately to normal, so it's lack of waterflow rather than cooling the water in the radiator, an electric water pump would do a much better job. If the engine is properly tuned we shouldn't have to use extra cooling fans, I think.

I'm still trying to find the right adjustments and I got hold of a Colourtune set that shows the actual flame colour in the cylinder, very handy tool, so I found that the engine was running a little rich at idle and adjusted the carbs accordingly, but found that this causes the temperature to go up under heavy load, I decreased the advance at idle from 20 to 15 degrees BTC and it reduced the temp again at heavy load.

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Regards,

Jim