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Block heater

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

scot850
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Re: Block heater

Post by scot850 » Tue Dec 04, 2018 10:41 am

i have used the block heaters on my P80 Volvos for years. Seldom any issues other than the heat transfer paste can disappear with time. I use heatsink (computer CPU) paste. You can buy it on line from good old China or Hong Kong for a reasonable price. Main issues are cable damage not the heater itself. They are getting harder to get as there are few still available through Volvo.

I have pulled a few over the years which are sitting in the garage in a box as yet another 'project'. I think I have some from 850's V/S/C 70's (P80) ans even one for a P2 I picked up for a buddy who then sold the car.

My only experience of water heated was a 99 Audi A4. Stupid thing nearly fell out from where it fitted into the block due to road salt corrosion. Stupid place to place it, and they became known for this issue, which rapidly drained the coolant and overheated the engine. When I asked the dealer to replace it they couldn't as Audi no longer sold it for an 8 year old car! The mechanic used the identical VW part.

I guess the viewpoint is right on both sides. Water heaters and the potential for major failure, or the inefficient block or oil pan heater. It is the oil you want hot to reduce engine wear when really cold, but it is nice to have the water hot to get the interior and windows clear quickly. Many manufactures like Audi now say that with modern oils you don't need engine heaters, but I beg to differ when it can get to -40C here in winter.

Neil
2000 V70 R - still being an endless PITA
2006 XC70
2003 Toyota 4Runner V8 Limited
2015 Kia Sportage EX-L
1993 850 GLT -Sold
1998 V70 XC - Sold
1997 Volvo 850 SE NA - Went to niece in California - Sold
2000 V70 SE NA - New project and test bed - Sold

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erikv11
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Re: Block heater

Post by erikv11 » Tue Dec 04, 2018 1:02 pm

Above all you want the block warm, the question is how you want to do that, pros and cons agreed. A thin film of oil smeared on an aluminum/metal engine surface will very quickly equilibrate to the metal's temperature. Same for coolant, that's why these systems are in place in the engine.

The coolant is only slightly larger mass than the oil, the ratio comes out to about 2-fold higher. But the coolant is dwarfed by the thermal mass of the engine, by a factor of roughly 7 times:

Heat capacities, based on specific heats (https://www.engineeringtoolbox.com/spec ... d_151.html, I used ethylene glycol value for the coolant):
coolant (7 liters) x (1 Kg/l) x (2.4 J/gC) = 15,200 J/C
oil (6 quarts) x (0.9 Kg/l) x (1.6 J/gC) = 7,800 J/C
engine (250 lbs Aluminum) x (454 g/lb) x (0.9 J/gC) = 102,000 J/C

That (huge differences in heat capacities) is why a good block heater goes a long way. The block heater heats all the coolant within the block but won't heat the coolant in the radiator, that is a weak spot but a minor concern. It also doesn't heat the oil. But passive transfer is slow, a coolant heater that also circulates the coolant is the quickest way to get it done, that works the same way the heat transfer does in the engine cooling scenario.

So yes, a simple block heater and oil pan blanket heats everything but the small mass of coolant in the rad, this strategy will warm things up really well without layering on more technology (to pump the coolant around) that brings more failure points.

I think the block heaters sold for P2 cars are only 300-400 watts, P80 was 500 watts, don't know why Volvo did that. Neil you could check the labels on the ones you have?
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WhatAmIDoing
'95 854 T5-R, Motronic 4.4, 185k
'96 855 NA, 145k
'98 S70 NA, 220k (living out west)
'98 V70, T5 tune-injectors-turbo, LPT engine, 285k
'06 S60 R, 165k
'99 Camry V6 :shock: 125k
gone: '96 NA 850 210k, '98 NA V70 182k

LOB
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LOB

Re: Block heater

Post by LOB » Tue Dec 04, 2018 2:46 pm

Swedish transport agency has researched the topic and concluded that heating the coolant is more efficient than heating the oil;
Quote:
"Energy efficient use of engine heaters – Evaluating the effect of heating lubricating oil compared to heating cooling water by Annelie Carlson, Ulf Hammarström and Mikael Bladlund The Swedish National Road and Transport Research Institute (VTI) SE-581 95 Linköping
Summary
Starting an engine when it is cold gives rise to higher fuel consumption and emissions as a cold engine means that a larger friction needs to be overcome and that the combustion is not optimal. To warm the engine in beforehand leads to lesser cold start effect. Traditionally, engine heating has been made by heating the cooling water, which in turn heat the engine block. The purpose of this study is to examine whether it would be more energy efficient to heat the lubricating oil instead of the cooling water. The hypothesis is that a warmer lubricating oil leads to less friction in the engine, which in itself would mean that less fuel to overcome the frictional resistance is needed. Likely, there may be differences in the usefulness of engine heater between cars with gearbox integrated with motor and without such integration. The test vehicle, with rear-wheel drive, has the engine and gearbox separated. A total of 23 tests were carried out; 2 without engine heating; 10 with heating of lubricating oil; 9 with the heating of cooling water and 2 with simultaneous heating of lubricating oil and cooling water. The results of the tests show that the cold-start effect with increased fuel consumption is reduced most by heating the cooling water. The warmer the cooling water is at engine start, the less fuel consumption by the engine start. When the total energy needs for cold starts is calculated, i.e. fuel consumption plus electric use due to engine heating, the results are not as clear regarding which option is the most energy efficient. The reduced fuel consumption as result of pre-heating is overcome by the electricity consumption needed for the actual motor heating. One advantage is that the local emissions will decrease. Since the Swedish electricity production to a large extent is based on emission free production technology, it is most likely that the total emissions are reduced."

https://www.vti.se/sv/Publikationer/Pub ... rva_725992

That coolant heaters are prone to cause leakage is not an issue in Sweden.

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WhatAmIDoing
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Re: Block heater

Post by WhatAmIDoing » Tue Dec 04, 2018 4:11 pm

LOB wrote: ↑
Tue Dec 04, 2018 2:46 pm
Swedish transport agency has researched the topic and concluded that heating the coolant is more efficient than heating the oil;
Quote:
"Energy efficient use of engine heaters – Evaluating the effect of heating lubricating oil compared to heating cooling water by Annelie Carlson, Ulf Hammarström and Mikael Bladlund The Swedish National Road and Transport Research Institute (VTI) SE-581 95 Linköping
Summary
Starting an engine when it is cold gives rise to higher fuel consumption and emissions as a cold engine means that a larger friction needs to be overcome and that the combustion is not optimal. To warm the engine in beforehand leads to lesser cold start effect. Traditionally, engine heating has been made by heating the cooling water, which in turn heat the engine block. The purpose of this study is to examine whether it would be more energy efficient to heat the lubricating oil instead of the cooling water. The hypothesis is that a warmer lubricating oil leads to less friction in the engine, which in itself would mean that less fuel to overcome the frictional resistance is needed. Likely, there may be differences in the usefulness of engine heater between cars with gearbox integrated with motor and without such integration. The test vehicle, with rear-wheel drive, has the engine and gearbox separated. A total of 23 tests were carried out; 2 without engine heating; 10 with heating of lubricating oil; 9 with the heating of cooling water and 2 with simultaneous heating of lubricating oil and cooling water. The results of the tests show that the cold-start effect with increased fuel consumption is reduced most by heating the cooling water. The warmer the cooling water is at engine start, the less fuel consumption by the engine start. When the total energy needs for cold starts is calculated, i.e. fuel consumption plus electric use due to engine heating, the results are not as clear regarding which option is the most energy efficient. The reduced fuel consumption as result of pre-heating is overcome by the electricity consumption needed for the actual motor heating. One advantage is that the local emissions will decrease. Since the Swedish electricity production to a large extent is based on emission free production technology, it is most likely that the total emissions are reduced."

https://www.vti.se/sv/Publikationer/Pub ... rva_725992

That coolant heaters are prone to cause leakage is not an issue in Sweden.
Interesting paper. Wish the full paper was available in English. Would love to read the experimental methods and raw data collected. Might try running it through google translate later. I do like that they took into account the emissions from electricity production.
'98 S70 T5M - 276,000+mi - forever a project
'99 S70 "AWD" - 220,000+mi - wrecked :cry:
Knows enough to be dangerous :wink:

LOB
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LOB

Re: Block heater

Post by LOB » Wed Dec 05, 2018 1:28 am

WhatAmIDoing wrote: ↑
Tue Dec 04, 2018 4:11 pm
LOB wrote: ↑
Tue Dec 04, 2018 2:46 pm
Interesting paper. Wish the full paper was available in English. Would love to read the experimental methods and raw data collected. Might try running it through google translate later. I do like that they took into account the emissions from electricity production.
I think Google translate works quite ok for swedish to english. Very of topic, but as a Swede, albeit tax payer in Norway, I appreciate that they occasionally fund som useful research. A large part of government research funds is lately given to completely meaningless and definitely unscientific "gender studies" such as "the ned for menstruation certified workplaces" (I'm not kidding). If you Americans thinks that some of your universities has gone mad, imagine a country the same way....

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