94 Volvo 850 T5 - Timing Belt Tricks Topic is solved

[Volvofan94]

Hello Guys,

Need your knowledge on a timing problem. I'm nearing the end of the cylinder head rebuild on my Volvo, but am struggling to get it back in time before I start the engine again. When I pulled the cams off originally I had them locked down, but during the reassembly process the old tensioner caused the belt to slip and everything got out of sync. The engine is back together with new belt and timing hardware, but the engine timing is slightly off. It spins over freely without valve to piston contact when things are tightened up.

At the moment I have a cam locking tool on to hold the cams in place on the back of the engine (per rspi's video). If I come to the front of the engine to look at the sprockets I see this.

Cam Locking Tool

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Cam Sprocket Timing Marks

IMG_0844.JPG (99.01 KiB) Viewed 3635 times

If I try to tighten the belt (working right to left) starting at the crank sprocket, to idler, to intake cam, to exhaust cam, then water pump and finally the tensioner, slack comes between the cams and the belt doesn't sit flush on the exhaust cam sprocket if I try to pull the belt tight.

Exhaust cam belt tension

IMG_0841.JPG (87.06 KiB) Viewed 3635 times

The cam oil seals have been replaced by a previous owner; maybe the shop got the sprockets out of sync during installation. I'm wondering if I should try to loosen the sprocket bolts and put things back to factory to fix the belt slack. Should I give that a try or is there another trick I should try first?

Appreciate your help and suggestions!

-volvofan94

[FLXC90]

Can you take a picture of the Intake sprocket, straight on, so we can see how the sprocket is referenced on the cam?

Since you have the cams locked out with the tools, you may be able to adjust the sprocket. PO may have adjusted the cam timing intentionally, or they may have understood that they had the sprocket indexed off by a tooth.

worst case, you could "ADD" a timing mark, knowing that the lobes are where they need to be.

[erikv11]

If the crank is on the mark, and the cams slots are locked horizontal, the engine is in time. Those cam sprocket parks are the last reference point. As stated, you can go back at the end and make sure those marks are where you want them, but timing is all about the crank mark and the alignment of the cam slots.

So seeing the sprocket hole alignment won't tell you anything about timing, just whether or not there is room to move the sprockets. So in that sense I agree with the last post - lock the cams, crank on the mark, loosen the intake sprocket to get the belt on, tighten it up. Rotate the engine, check the crank mark and the cam slots.

[Ozark Lee]

It looks like I can see an old outline of the bolt on the exhaust sprocket. Typically the sprockets bolt up in the center of their travel in the slot but if you need to play with that adjustment it doesn't hurt anything. I don't think I have had one yet where both marks on the sprocket were exactly dead center on the V notch on the cover. One or the other has always been a fuzz off with the crankshaft at the mark.

...Lee

[Volvofan94]

Thanks guys for the quick replies!

The engine is now in time. It starts, runs, and idles beautifully. I followed the steps suggested then voila it's one step closer to being roadworthy again! I didn't need to adjust the cam sprockets; I lined things up on the back of the engine using the locking tool and worked the belt around enough to get the marks on the sprockets and crank to line up then the slack was in the correct spot on the water pump and tensioner side.

Now onto another problem....what is the best way to remove or move the exhaust manifold without removing the cylinder head again?

When the cylinder head went back on the exhaust manifold gasket for cylinder 3 slipped off its studs.

[tryingbe]

Now onto another problem....what is the best way to remove or move the exhaust manifold without removing the cylinder head again?

When the cylinder head went back on the exhaust manifold gasket for cylinder 3 slipped off its studs.

Take the turbo off and exhaust manifold will come off easy.

Drilling and tapping... not so much. I'm not sure you even have enough space back there unless you have a 90 degree drill and can get the stud off completely before drilling. Those studs are stainless steel, very hard to drill with the aluminum surrounding it.


I punch some dots into the camshaft and its pulley so I can always align them correctly, never have any issue setting timing.

[Volvofan94]

Got some good news, the car is now in time and I was able to get my exhaust gaskets repaired too. Installing the exhaust gaskets on the head with the studs removed was trial and error, but in the end it worked out well.

Thanks again for all your help and advice!
-volvofan94