I bought a 1994 940 NA a few weeks ago and have been trying to get it in good condition. The distributor is on the end of the camshaft so the idler gear has no effect on cam to crank timing.
I replaced the timing belt and tensioner about a week ago and today I retensioned it with the engine at #1 TDC. The belt was a Contitech and I noticed when I replaced it that the mark on the Scantech innermost cover was off a little, about half a cog too much clockwise. But the car ran fine. After retensioning the belt today I started it up and the idle speed was about 1500 RPM. Before the retensioning, idle was at the normal 750 or thereabouts RPM. I then moved the timing belt one cog counterclockwise. The idle speed was then about 1300 RPM.
I compared the Contitech markings to a new and old Volvo timing belt and the distance from the double mark (the crankshaft) to the mark going to the camshaft was one cog too much.
I have used Contitech for many years with no problem but the two Contitech I compared with the Volvo timing belt have them 1 cog too much (crank to camshaft markings). I bought the Contitech timing belts a couple years ago.
I don't know if retensioning the timing belt changed the timing enough to cause the high idle or it was a coincidence with something else going wrong??
Also, I am wondering if the cars I have replaced the timing belt with Contitech are timed correctly?
So, has anyone else noticed the incorrect marking on the Contitech timing belts? Also, why is my idle so high after retensioning the timing belt or is this a coincidence with some other problem?
Thanks!
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Mine:3-940s running, 1-740, 2-940 parts, dtrs:4-940s running

I think I might have figured it out. The Volvo belt is of course correct. The Continental belt TB324 (round toothed) has the exact same teeth, pitch and length as the Volvo belt. But note that Contitech and others list the fitment as not only for later Volvo 940s and 240s, but also other engines such as 2000-2003 Hyundai Accent which may well have slightly different sprocket timing marks. I'm sure after 25 years you can forgive Contitech for possibly trying to save a dollar and combine otherwise identical products under the same part number. If they were more observant, they'd have dropped the white lines completely in order to avoid confusion, or perhaps the engineers didn't notice that the belt markings for Volvos are a mere one tooth different and someone thought they were identical in all regards.

The other possibility is a simple mixup on the production line that may have extended for many months or even years worth of stock where the white lines were incorrect for both Volvos and Hyundais. Installed properly by a trained professional mechanic where sprocket timing marks should always take precedence, it's possible no one has ever had an engine running issue and if they did, they never complained to Contitech.

No matter what the white lines on the belt or which way the belt is facing when it's mounted (it makes no difference which way), what matters most is having the sprockets properly aligned for installation and that the belt is wrapped in order to keep the non-tensioned spans fairly taught so as to preseve sprocket alignment when properly tensioned. After installation, always rotate the crank a couple of times and re-check the timing sprocket alignment marks in addition to the belt tension. The exception of course is the intermediate shaft on the later 740 and 940 B230s which have their distributors on the back of the cam and the sprocket timing mark makes no difference other than to satisfy idiots like me. I've never done the actual calculation, but it would likely take several hundred revolutions for the belt marks to line up again with the sprockets.

Now that we know this kind of thing can happen, the white line markings on all makes of timing belts should be taken as suggestions at best.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Thanks Dale Stevens for the great timing mark explanation! I didn't realize the 2000-2003 Hyundai Accent also used this belt.

The two sprockets and crank do line up if the single white lines are moved 1 cog on the Contitech belt.
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Mine:3-940s running; 1-740, 2-940 parts; dtrs:4-940s running

I've followed this thread and realize, in my ignorance, I've been doing it right all these years--on my own cars and those of others. I've always used Conti belts and could never understand what the 2 lines represent. I set the crank to the mark and then line up the single lines at the cam and auxiliary shaft -- and not worry about where the 2 lines end up. Always worked for me.-Dave

Yep!
What your doing in the best ways!
Get them lined up and belt taut between them!
Sort of ignore those lines, as in, the double one has to be imagined to lay over into the tooth next to or in the on the mark.
It goes back to a possible error in counting the next tooth on the belt and then the dotted tooth on the sprocket,
Then there the crankshaft with its to the casted mark that points to a notch that’s the bottom of a tooth.

Maybe the double lines can mean you have a choice down there? (:-)
To be confused or not to be? Not liken to be within a Shakespearean experience though! (:)

Phil

I had a 1994 Volvo 940 natural aspirated B230 engine but it had the distributor on front of the engine. When I changed my timing belt I found out that the 940 engine had a different belt than a 240. If I recall it a few more teeth on it but don't quote me on that since my memory ain't that good. I would do some research that you have the correct belt first of all.

Our 7 940s 1993 - 1995 all have the round tooth belts.
I am wondering if there are a lot of 940s out there running with Contitech timing belts out of time by 1 cog?
I rechecked my 4 spare Contitech belts with my 2 spare Volvo OEM belts and the single line markings are 1 cog off. I assume the Volvo OEM belts are correct since they make the markings on the cam, dist. and crankshaft line up with the markings on the back black plastic cover.
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Mine:3-940s running; 1-740, 2-940 parts; dtrs:4-940s running

Hi,

I don’t know how you are counting the teeth on the belts but I doubt the belts themselves vary with numbers of the teeth all that much.
Every belt I have ever used went on without any problems and have 123 teeth in total.

The total length of the belt is actually almost considered irrelevant as long as the tooth spacing and its form matches as the tooth pitch on the sprockets.
That thing could go out and around out the fenders as long as it’s taut between the three sprockets, on the pulled side and the marks line up.
Nothing is going to get out of time unless the belt is NOT taut!
That’s why there is an adjustment service interval required!

When an engine stops, the Pistons can actually equalize themselves in the cylinders, due to compression build up and can back up slightly.
If the belt gets too loose that’s when the belt can jump a tooth or a rapid acceleration or stall out can move it more than one tooth!
It’s very important to reset the tension during every other 7,500 mile oil change. It only takes a moment!

You really don’t need any marks on the belt as long as you keep the marks in place, when the right side taut between the sprockets on either side of the distributor sprocket. That it the timing part!


Counting Line to Line, of which, is the top of each tooth “on the belt” is how it works for only the belt!
The sprockets count on the bottom of a tooth root where it’s suppose to go.
You only start out counting over from dot on any LENGTH between either of the sprockets to one!
You cannot count both dots.
If you cross from the top to a bottom engagement system, it won’t come out right.
Otherwise you end up one tooth off!
44 teeth on the upper length spacing and 27 on the bottom. That is what I count with those lines drawn on the belt.
That leaves 52 on the backside to go back to the top of which is “all” tensioner location take up.
Nobody wants to count, but the snafu is, the crankshaft sprocket does not get wrapped with the belt upon installation.
The last tooth engages over, if you use lines, to mark bottom.
You have to imagine that belts teeth laying over to the bottom of the tooth that will line up to the marked tooth.
Remember you can only count one mark on either end of a set length.
So the last line, is up on the left, about three teeth high, if I remember correctly.
I know that sounds odd but the crankshaft has to divide equally into diameters to get a TWO
to ONE ratio up top. Those other things travel at half speed on four stroke engines and all that sounds even!
Well!
Luckily the crankshaft rotates the belt around at about six times slower than the engines RPMs
I’m saying the belt itself slowly rotates it’s length around and around within a 360 degree circle.
This is why after you rotate the engine, to double check your marks for synchronization, those painted lines on the belt never line up again unless you turn the engine over and over several, several times!

I’m suspicious that its about three degrees of rotation with each trip around on that 123 tooth belt.
With a longer, out to the fenders belt, it would even take longer!
What’s nice is this helps to rotate the wear around the belt, ever so slightly so it never stays in one place over and over. Like it could…(:)

Yeah right, now I bet that plays with one’s mind!
So it shows that only “one side” of the belts location is doing the timing of anything and it’s a round thing and there are no “sides” except the inside and outside? (:) Do edges count? (:)

So please don’t count those teeth anymore or you could go blind! Adjust the belt regularly and call it good!
Also, for better maintenance practices, don’t ignore the cleaning of the teeth in your head, as they will skip out and go away too! (:)


Phil

Thanks Phil but how do you explain the side by side comparison of a Volvo OEM belt and a Contitech. Here's a picture I took. Also, there are identical numbers of cogs:
https://brickboard.com/IMAGELIB/volvopic.htm?js_link=1&id=13906
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Mine:3-940s running; 1-740, 2-940 parts; dtrs:4-940s running

Hi,

I think Dave Stevens has answered your question better than I can. His reasoning is right on with my knowledge of manufacturing and the things they do to sell products!

As far timing belts go they are already “dialed in” or perfected for sprocket engines.
This makes me think Dave Stevens has the correct answer with the idea of many other engines out there!

I have used Volvos belts and Continental timing belts for years. I could see no difference in quality myself and I know manufacturers will and do shop around, just like we do!

This is one of many reasons the Bricks have done so well over the years with model continuity!
I have always considered Volvos forward thinking simplicity, as an enduring quality.

With Today’s line up though, they’re just as nuts as they come! $ 50-60K a copy?
Our cars already look exclusively different without trying!

Phil

Hi,

I think you are correct that the timing belt is different than all other of the 240’s except for the last year of which was 1993.
The 1993 240 uses a rounded tooth belt and sprockets!
This is where the changes of many started within the 1992-1993 years.

The 900 series cars are using the same red blocks with on going subtle changes!
So make sure you have the rounded tooth belt before starting the job.

Phil

I replaced the Tensioner and Timing Belt on a daughter's 1995 940 NA. The Timing Belt was a new Contitech and I saw the same problem again i.e. the single belt marks were 1 cog off relative to the double belt marks that line up with the crank keyway. I verified the new Contitech belt was marked off one cog with a new Volvo OEM belt. Re-marking the Contitech belt to be the same as the new Volvo OEM belt and installing it, the 2 single lines lined up with marks on the cam gear back plastic housing mark, dist. drive gear black plastic housing mark, and the double line lined up with the crankshaft keyway.
So, it is important to make sure the gears and black plastic housing marks line up as well as the double line lining up with the crankshaft keyway and the only way to do that is to ignore the Contitech single line marks or remark them.
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Mine:3-940s running; 1-740, 2-940 parts; dtrs:4-940s running

Dear jd620,

Hope you're well and stay so. Thank you for a truly helpful report!

How did the car run, with a one-tooth timing belt misalignment?

Yours faithfully,

Spook

Hi Spook,
I remembered the problem from a couple years ago so re-marked the Contitech belt, using a new Volvo OEM belt. Things lined up perfectly, gears marking to black plastic back cover, and the engine ran great.
It kinda makes a person question the Contitech belts but folks here seem to think they are good. I have four new ones to use.
Thanks for the post.
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Mine:3-940s running; 1-740, 2-940 parts; dtrs:4-940s running

Here is a link to a picture of the two new timing belts side by side. Both the single line marking on the Contitech were off by 1 cog compared to the OEM Volvo.
https://brickboard.com/IMAGELIB/volvopic.htm?js_link=1&id=13906
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Mine:3-940s running; 1-740, 2-940 parts; dtrs:4-940s running

Contitech belt marks are correct,,look closely at the diagram for installation

Here is a link to a picture of the two new timing belts side by side. Both the single line marking on the Contitech were off by 1 cog compared to the OEM Volvo.
https://brickboard.com/IMAGELIB/volvopic.htm?js_link=1&id=13906
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Mine:3-940s running; 1-740, 2-940 parts; dtrs:4-940s running

I always have used Contitech timing belts and have never had a problem similar to what you have found.
I will suggest this regarding tensioning - or - retensioning the belt -- it does not make any difference where the crankshaft timing is when you set the tension. What matters is that any slack is set to the tensioner side. Loosen the lock nut for the tensioner, rotate the crankshaft clockwise about 30 degrees or so to take any slack out of the camshaft-idle gear-crankshaft side. Tighten the lock nut.
After posting the preceding I thought to add this. Personally I've never figured out what the double line is supposed to match--basically I ignore it and just make sure the camshaft and idle shaft marks align (on 240 models) and the crankshaft is truly at TDC. Question--are the total number of teeth the same between brands? If so - I wouldn't be too concerned over lines on the belt on your 940. With the camshaft set to the mark on the head and the crankshaft aligned with the nub on the front crank seal housing it will all work. - Dave

The IPD timing belt video enlightened me as to the double line. If the belt were wrapped around the pulley, the double lines would line up with the key-way.

https://www.youtube.com/watch?v=jVZ-DpDX1TQ

Interesting that in the video they mentioned the ways to remove the crank bolt and an impact wrench was one of the ways. The FAQS have said to not use an impact wrench because it might break the crankshaft. I have used one many times with no problems.
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Mine:3-940s running, 1-740, 2-940 parts, dtrs:4-940s running

I have always used an impact wrench. I doubt they used the rope trick when they assembled it in the factory.

I double star washered the 2 fuel injector grounds but no help.

The car has 2 grounds added from battery minus to ABS assembly frame and fuel injector rail to strut tower. So, a previous owner must have had ground issues.

It is 47 Fahrenheit out and the car has been cooling off for the last 4 hours. I started it up and the idle RPM was normal, about 750-800 RPM. As the engine warmed up, maybe 5-10 minutes, the RPMs increased to about 1300. Something is heat sensitive. I'm wondering if the ECT (sensor under #3 cylinder) is bad. Are there other things that are heat sensitive by design that could be causing the high idle?

Thanks

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Mine:3-940s running, 1-740, 2-940 parts, dtrs:4-940s running

the throttle body mustve a leak,,maybe the grommets on the throttle shaft

i always use a soft nylon rope in through the spark plug hole

In the past, I have always lined up the marks on the inner cover and crankshaft. I just find it strange that the Contitech and Volvo timing belts are marked different.

Any idea why the idle should be so high all of a sudden? What determines the idle RPM? I thought it was computer controlled. I checked the throttle body micro switch with an ohmmeter and it is good.
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Mine:3-940s running, 1-740, 2-940 parts, dtrs:4-940s running

Dear jd620,

Hope you're well. See if the Idle Air Control Valve (IACV) needs cleaning. A very dirty IACV can stick. See the FAQs for the procedure.

I use throttle body cleaner to remove dirt. Be sure to keep the IACV'S hose-end pointed downwards, to keep cleaning solvent from entering the motor chamber.

Sometimes, cotton-tipped swabs help to remove caked-on grime. Be careful not to leave behind any cotton fibers.

Hope this helps.

Yours faithfully,

Spook

Thanks Spook. Cleaning the IACV didn't help. I actually cleaned it twice with Throttle body spray.

Could the temp. sensor under #3 intake be bad?

The problem began after changing the timing belt and not right away. Right after I cleaned the throttle body and the IACV the first time everything was okay for a half hour or so and then all of a sudden the problem started when I started the engine i.e. idles at 1300 or so RPM. Normally idle speed is 750-800 RPM. I have also checked the throttle body microswitch 2 wires that break connection above idle. I don't know what the 3rd wire does?

The car runs great on the road.

Besides the temp. sensor, I wonder if the ECU computer went bad. I have never had one go bad in the 34 years I have been driving 240s and 940s but I suppose there is a first time.

I 'd appreciate more ideas.
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Mine:3-940s running, 1-740, 2-940 parts, dtrs:4-940s running