This is on what I think is an 81 B21F and I have no idea what it is for. Please help me figure this out. Thanks

I have one on my '80. The wire leads down to a sensor(?) that probes into the flywheel area. But I didn't see a matching magnet(?) on the flywheel, so don't know how it works. Wire is fried from exhaust heat and I have had the urge to remove it since it appears useless.
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1980 245 Canadian B21A with SU carb and M46 trans in Brampton, Ont.

Yeah I think I will remove mine too. No need to have it in the way if it is useless now.

It's a diagnostic test point for dealer repair shops...could read timing and RPM and I'm not sure if anything else. Saved them from using a timing light and a tach That is a B21.

Why oh why don't they make 240s anymore :(
75 245(RIP) 80 244 226K, 87 245 172K

I forgot to mention that the other end of the wire goes into the bellhousing.

It's a crank position sensor plug used by the dealership in some diagnostic equipment. Set your engine to TDC and you'll see two small magnetic dowels at the 3 o'clock and the 4 0'clock position. The sensor in the bellhousing reads those...

My son's 81 B21F (Calif. spec) has the plug. In my early 80's shop manuals, certain engine tests call for the "Volvo Monotester" which just looks like a big ol' automotive multimeter from the 70's. I think it gets plugged in to this.
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Bob (son's 81-244GL B21F/M46, dtr's 83-244DL B23F/M46, my 94-944 B230FD and 89 745 (LT-1 V8); hobbycar 77 MGB, and a few old motorcycles)

Sorry -- you are right! It's called the magnetic timing sensor (is independent of distributor timing or it's built-in advance), and is found in the MPG version of the B21F. It's meant to be used with a dealer unit called the Magnetic Timing Unit.
[I got this from my Green manual: New Car Features, 1981]

Ken, this device predates the B21F MPG engine by at least a couple of years if not more. My '79 242 had one as does my '80.
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'80 DL 2 door, '89 DL Wagon

Thats funny my '80 dosn't have one, and this block has a date stamp of '81. What was differnt about the MPG engine compared to the normal B21?

Maybe they didn't all have them. Maybe your '80 had one and it was removed. I suppose it's possible that they could have been retrofit on my cars I, but I sort of doubt it.
I can't remember exactly what's what with the MPG engine. Lower friction, I think, so less main bearing surface, maybe? Lighter pistons? I don't know for sure. Ken C, if you see this, is that info in the greenbook you mentioned?
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'80 DL 2 door, '89 DL Wagon

I bet no one here can tell me what MPG stands for.......

I wasn't at all familiar with the B21F-MPG variant, but your little challenge on the meaning of the MPG designation has changed that a bit. I'm sure most of us thought of MPG as Miles Per Gallon, but immediately dismissed that simplistic and likely irrelevant thought. Curiosity got the better of me, so I fired up Google and off I went.

I hit paydirt on K-Jet.org. All you K-Jet people should bookmark that site. It's full of goodies, from model descriptions to a fairly complete set of 1981-era green manuals, the 1985 240 wiring diagram manual plus assorted Volvo brochures and magazines.

I found out that the B21F-MPG is also called the "B21F-9" (presumably from its engine code of 49) and was sold as a "new" option on 1981-1982 242DL's (2-door) in the USA only, both Federal (49-state) and California. Quoting from the K-Jet.org site, "My guess is that Volvo didn't sell a lot of 1981 B21F-9 motors and so they just stuck the leftovers in the 1982's". It was one of a number of variants of the B21 4-cyl red block engine in those days. Other USA engines were the regular B21F ("B21F-5") and the B21F-turbo ("B21F-7"). Canada got the B21A (with SU carbs) and the infamous B23E (fuel injected -unabridged power without a turbo). I'm sure there were additional carbureted versions in Europe and elsewhere. That connector hanging on the MPG valve cover is described in the green manual as the "Magnetic Timing unit connector" as described by others -primitive perhaps, but quite useful.

From the following notes you will see that the MPG was a low powered beast with a low idle speed and low rear axle ratio. It was designed as a gas miser, B21F-lite if you prefer. So MPG as "Miles Per Gallon" is a legitimate designation for marketing purposes driven by the high gas prices at the beginning of the Iran/Iraq war which when adjusted for inflation were higher than today's prices. The only technical names I can guess at would have something to do with Magnetically Programmed Timing or Mopar Programmable Timing or some such in Swedish (where "gang" means "time"). I also saw mention of an MPG M-grind cam, but not in the official Volvo literature. Am I close?

Here's some (interesting) comparisons of 1981-era B21F and related engines: This is all info I tripped on in the offical green manuals and probably more than anyone needed to see in this thread.

All B21F variants had Bosch electronic ignition, except the MPG which used Chrysler Mopar. All fuel injected models had Bosch CI "Continuous Injection". All USA models had Lamda-sond O2 sensor, catalytic converter and ran on regular unleaded fuel (unleaded or leaded in Canada). All automatics got the AW55, except USA wagons and all Canadian 240's, which got the BW55. For manuals, the M46 was found on all GL/GLT's & some DL's, the M45 was found only on DL's. Rear axle ratios in the USA were all 3.73:1, except 3.54:1 for the MPG. In Canada, rear axle ratios were 3.91:1 on all DL manual's, 3.73:1 on all DL automatics & GL/GLT manuals, and 3.54:1 on GL automatics.

** B21F (B21F-5)** 240DL & 240GL (USA), CIS "Constant Idle System" (California only), 9.3:1 compression ratio, 107hp@5500, 114ftlbs@2500

** B21F-MPG (B21F-9) ** optional engine in 1981 242DL (USA), standard in all 1982 DL's (USA) before 1982 LH-Jet, CIS w/low 750rpm idle (vs. 900rpm all others), 9.3:1 compr, A-cam in 1981 (B-cam in 1982 like the B21F-5), Mopar ignition system, 99hp@5000, 114ftlbs@3000, 3.54:1 rear axle (vs. 3.73:1 all other USA), no sunroof, manuals had no power steering (unlike most others)

** B21F-turbo** 242GLT (USA), CIS, 7.5:1 compr, T-cam, 126hp@5400, 150ftlbs@3750

** B21A ** 240DL (Canada) w/Pulsair EGR, w/o Lamda-sond, w/o cat, reg leaded (or unleaded), 8.5:1 compr, 96hp@5250, 125ftlbs@2500

** B23E ** 240GL & 242GLT (Canada) w/Pulsair EGR, w/o Lamda-sond, w/o cat, premium leaded (or unleaded), large displacement, 10:1 compr, K-cam, 129hp@5500, 135ftlbs@3500, 3.54:1 on GL automatics (vs. 3.73:1 on manuals)

USA market 240's were almost exclusively built in Sweden, but a few USA configurations may have come from the Halifax plant in Nove Scotia, presumably when the much touted production teams were about to run into a dry spell (lest they get into the Alexander Keith's). Most of the early Canadian market 240's were built (assembled) in Halifax, but some also came from Sweden, presumably to keep up with excess demand (early 245's come to mind).

e&oe.
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Dave -940's, prev 740/240/140/120 Never overestimate what little I know.

Nice report Dave, with cites and all.

I always figured MPG meant the obvious. I know it has nothing to do with the aforementioned diagnostic connector for the Mono-Tester, as that was around years before '81. Most did get lopped off when the wire got in the way draining the block or changing the cam cover gasket. One of mine was obviously crispied by an exhaust gasket leak in its life with a previous owner.

Given the era, I think MPG had marketing power. The '82 New Car Features book is by far the thickest in my collection at nearly 100 pages. All it says about the name "MPG" is the desgination was made to identify the CI engine "to separate it from the other engines". By 82, all non-turbo (US) k-jets were MPG, or 49 code, according to the manual, and I expect the LH1.0 new to '82 took over in the quest for higher gas mileage.

Good thorough post you've written. I wonder what the advertising and owner's literature says about the MPG name?
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Art Benstein near Baltimore

If your dog is fat, you aren't getting enough exercise. -Unknown

Thanks, Dave for the good write-up. I agree that the k-jet.org website is a great resource. One thing I find interesting about my '81 242DL is that it does have a MPG engine but also has power steering (with my M46 manual) so I wonder if PS was an option. I do get good gas mileage, but my idle has been somewhat rough lately. May be time to mess with the idle screw. Another project for the weekend!

By the way I don't think I have that diag port but I could be wrong.

Odd about your power steering. The table on page 10 in the '81 Volvo "New Features" green manual says none of the B21F-MPG manuals got power steering. It may have been an option, but I kinda doubt it, yet it sure wouldn't be the first error in a green manual as production changes do occur, probably from plant to plant, what's in their parts inventory and as the next model year is starting to roll out. Your car may have had some aftermarket work done. Changing the rack and adding the power steering pump wouldn't be too difficult from a donor car. Hacking off an unused timing diagnostic connector would seen reasonable if it wasn't being used as it looks like it was mounted in one of those cheap vinyl valve cover clips (like the spark plug wires use) that break after a few years (check to see if there are remnants of the wiring on the top of the bell housing). More definitively, you can check to see if your car originally came with an MPG engine from the VIN -it should start YV1Ax49. More detailed is the Version Identification Code (on the left door jamb and on the left firewall) -it should go:
24 =240 series (26=260 series)
2 =2-door (4=4-door, 5=wagon/estate)
49 =B21F-MPG engine code (41=B21A, 45=B21F, 47=B21F-turbo, 69=B28F, 77=D24, 84=B23E)
02 =DL sales model/trim level (03=GL, 06=GLT, 07=Coupe/Bertone?)
3 =no sunroof (4=sunroof)
2 =M46 manual (1=M45, 6=AW55, 8=BW55)
1 =left hand drive (2=right hand drive)

The bottom line of the VIC plate indicates the steering gear:
1 =Cam Gear power steering
2 =ZF power steering
NB. They don't list the code for manual steering and I couldn't find it elsewhere so let's assume it's zero or blank. The steering codes for the 240 changed somewhere between 1976-1980.

All this is found in the documentation on the K-jet.org site.

Oh, and one more factoid about the B21F-MPG, the transmission (they don't say which one) had a lower first gear ratio of 4.03:1 (same as the diesel).
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Dave -940's, prev 740/240/140/120 Never overestimate what little I know.