62 544 overheat questions

[Derek UK]

Not sure that the 6 blade fan shown is actually Volvo. They are usually 4 bladed. The 4 blade ones may be more efficient but as said the 5 blade plastic ones are good. Not cheap but should be available from Mike Dudek. Some fans on some engines use a spacer which positions the fan closer to the rad and this should be used if it still allows a small distance between the fan and the rad. Closer is better.
Adding an adjustable thermostatic switch to your electric fans a good idea, keeping your switch as an override.
I'd say that the gauge pointer positions in the conditions you describe aren't out of the ordinary and wouldn't be too worried. The fans in front of the rad do obstruct the flow through the rad a bit and you have to take that into account.
With a good engine fan the electric fans should only come on below at about 30mph but at raised temps and climbing in the hills under load that would raise the coolant temps and cause a switch on.

[arcturus]

One other thing, put heater in on position and close vents. There could be up to 1/2 ltr coolant in heater matrix which would help with cooling.

Derek, I agree with you on elect' fans cutting down airflow.I have found that to be the case. A "pull " fan would be better if there is room. Some folk remove the cooling fan altogether and just have the elec't ones come on by the thermostat. Engine fan not doing much once you get going. Also quicker warm up.

[Ron Kwas]

Guys;

I agree that anything in the path of airflow "restricts", but I disagree that it is in any way significant!...any restriction those blades might cause is minimal and certainly would not affect the heat exchange at the Rad downstream to any significant amount...! ...take a look at any elec cooling fan frontally...you can easily look right through the blades (it is nowhere near a positive displacement "pump"), and this will allow a nearly unrestricted airflow...also...when the motor is not energized driving the blades, they freewheel in the breeze being backdriven by the airflow through them, making airflow through them even easier, and less restricted...heck, you could conceivably use this windmill effect as an energy generator, but the ever-so-slight disadvantage of installing an ECF can only be an advantage in terms of moving air when its needed!

Cheers

[lelshaddai]

So are you saying that if the tubes are blocked that it would hold less coolant, thus the reason to measure how much? When the radiator was out the water seemed to pass through it about as fast as it goes in. I just cannot figure this out. I will test many of these theories out when I get back from the show.

[arcturus]

Checking the amount of coolant the unit as a whole holds can give a good indication. Coolant doesn't need to pass through all the matrix tubes to run out the bottom. I don't know what the capacity of you rad' (is it an rad from a PV b18/b20or some other?) is.

[lelshaddai]

It is original radiator whether for the B18 or the B20 I do not know.

[arcturus]

Is it pressurized, connected to an overflow bottle? Post a picture when you get back home.

[lelshaddai]

Here is another thought. I went to the show this weekend with a buddy. During the long car show parade of vehicles my friend mentioned that I was burning oil. Many on the downshifts and taking off. That would explain why I was low on oil. Will be doing a compression test and leak down test Monday. Hopefully it is valve seals and not rings. My friend is a mechanic and he thought the dieseling/run on is from carbon build up on the pistons from the oil leak. The carbon is super hot and ignites. Thought then is whether this may cause overheating.

Another note. The manual for the b20 says compression to be
156-185 for B20A or 185-200 for B20B. That seems really high. How do I tell which I have and is that realistic pressure?

[arcturus]

B20a, 8.7:1. B20b, 10:1

[arcturus]

Worn valve stem seals can lead to oil being consumed. Had a similar problem on my B20. New seals cured it.