850 timing marks are off

Post by **fastgroceries** » 05 Jan 2018, 00:12

I'm changing the timing belt on my 96 Platinum sedan and found that both the exhaust and intake cams are both retarded a couple degrees. I saw a tool provided by IPD that helps adjust the physical timing, and the tool's manual explained the situations where advancing the physical timing would be beneficial.

see https://www.ipdusa.com/products/7047/11 ... iming-tool

From the photo I am attaching I had found that both cams were retarded a couple degrees.
I have my cam-lock tool inserted into the block, to the crank is exactly at TDC..

Does this look intentional or was the last time it was reassembled was it "one tooth off" ?

Post by **RickHaleParker** » 05 Jan 2018, 01:37

The camshafts do look like they are in time with each other. I don't see the marks on the crankshaft sprocket and block aligned.

Using the 30mm nut on the end of the crankshaft, align the mark in the crankshaft sprocket first, then check the alignment of the camshafts. It looks rather dirty down there, clean up down by the sprocket so you can see the marks.

Always rotate the crankshaft clockwise as viewed from position you took the picture. If you turn counter clockwise the belt can slip.

Post by **abscate** » 05 Jan 2018, 05:00

You do not time these cars at TDC. The "timing marks" do not represent TDC, but marks where all the valves are clear of the Pistons, which is " every piston NOT at TDC"

You can't use the cam lock tool to confirm cam piston. Many of them, including mine are slightly off, the function of the cam lock tool is to ....lock the cams

As posted above, line up the crank first, get that right, then set the cams to the marks, then install the belt.

Then turn the belt twice with the 30 mm to confirm all three marks align.

There are many great threads on the -1998 belt, fir 1999- you heed the CVVT belt procedure

Post by **RickHaleParker** » 05 Jan 2018, 06:02

It is possible that somebody used one of the marks on the sprocket as the reference instead of the valley between two marks, or the wrong valley. Regardless, the marks on the sprocket are the datum, until the datum is confirmed to be correct, everything is meaningless.

Post by **FLXC90** » 05 Jan 2018, 12:38

How long have YOU owned the car? Is this the first cam belt check? Might the Previous owner put a tune on the car?
You say you installed the locking tool in the notches at the rear of the cams to lock them at horizontal, correct? As posted, verify the lower timing marks are aligned.

Post by **RickHaleParker** » 05 Jan 2018, 13:05

You say you installed the locking tool in the notches at the rear of the cams to lock them at horizontal, correct?

He said he installed it in the block, I think he speaking of a Crankshaft Alignment Pin not a Cam Lock. The way to verify a Crankshaft Alignment Pin is set correctly is to look at the marks on the sprocket.

Post by **fastgroceries** » 05 Jan 2018, 21:29

Yes I have the 'crankshaft alignment pin' in place. So the piston is held at TDC.
I have owned this car since February, and this is my first attempt at a DOHC timing belt, but have done several SOHC belts before.
I guess I'm asking if I should align the cams with the camshaft lock tool? Or..line then up with the timing marks.
The camshaft alignment tool sets at TDC, then this photo may be correct. Cams are then 'a few degrees before TDC'.
There is a sticker for the shop that last changed the belt, and they are the most reputable independent Volvo shop around here.
So just lock everything down where it is and change the belt??

And Thank you all for your replies!

Post by **jimmy57** » 05 Jan 2018, 21:58

You'll need the black plug for the back end of exh cam, but checking or adjusting is best done now. (You may be able to get the plug out and then seal the hole in it with RTV.) If you pull the CPS and the plug and the slots are parallel with the head top bottom spit line then the gears were pulled for seal change or something and it was timed right but the gears are just off from prior position. The gears can be a tooth either way usually and it will be in time. The gears are not made with marks. the engine is built with the index tools and the marks are scribed last. If you buy new gears there is no mark, you do it when you install new part and index everything. There are lots of no key ways, no marks engines around that only use the tools. The head gasket thickness deck (block) height, and if the head gets machined then engines like this will still be timed right. Keyway geared engines have no comepensation (usually) for these things.

Post by **RickHaleParker** » 05 Jan 2018, 23:45

Yes I have the 'crankshaft alignment pin' in place. So the piston is held at TDC.

It is possible to get the crankshaft alignment pin incorrect.

1. Line up the mark(s) on the crankshaft timing gear with the mark on the oil pump.
2. Place the starter motor to one side.
3. Remove the blind cover plug and cover washer.
4. Turn the crankshaft clockwise slightly to avoid the adjustment tool being in the wrong position.
5. Install crankshaft crankshaft alignment pin.
6. Ensure that the alignment tool bottoms out against the cylinder block.
7. Turn the crankshaft back counter-clockwise until it stops against the drift.
8. Check that the mark(s) on the crankshaft timing gear corresponds with the mark on the oil pump.

Post by **FLXC90** » 06 Jan 2018, 10:44

Yes I have the 'crankshaft alignment pin' in place. So the piston is held at TDC. OP this is a misconception. The pin holds the crankshaft at an indexed position where NO piston is at TDC. This way, you could take the belt off and spin the cams if you wanted, and have no interference. It's a safety thing. If you remove your cam position sensor and distributor, there are slots in the tails of the cams. Their basic reference is horizontal. NOTE: one sits above horizontal, one sits below horizontal.

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