Little help here so I don't F this up.
I just got done replacing all my valve stem oil seals with head still on....20 of them!
So now I need to get the T belt on.

Big Question: when aligning the crank shaft to TDC, it appears the crank sprocket TDC notch can align with the block mark at either phase of cylinder #1 being at top of compression stoke OR top of exhaust stroke.

Does it matter which one I choose?

Thanks all

Rob

Yes, it matters. When the crank is on the mark, that is the compression stroke of #1. It is easier to align the cams on the rear, with the slots being parallel.
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My name is Klaus and I am a V♂lv♂holic

But my camshafts are off.
I am putting the camshafts back on with the valve cover. I will keep those rear camshaft slots aligned per shop manual.

So before placing the top assembly on, the #1 cylinder needs to be TDC.

So it doesn't matter if #1 piston is at TDC on compression or exhaust?

Rob

Rob

I have to chime in bacause nobody caught this serious error. When the crank mark is aligned for matching the cam marks (sprockets or slots), number one piston is NOT! at TDC. It is 90° before, ergo halfway down, so that no piston is at TDC (5 or 6 cyl version). Is is one of the few safe positions to ensure that piston-valve contact cannot occur no matter when the cams are.

If you use the crank mark or Volvo locking tool before placing the camholder down, you're safe. If you put #1 at TDC visually and then put it together, it wont run.

I considered that as we sat here and referred to "TDC" on the crank sprocket, knowing that wasn't exactly accurate. But since Rob wasn't pulling the head off, I figured he was not goint to probe #1 piston for actual TDC and was just going to align marks on crank/cams to get it all back in sync.

If he never seperated the cam sprockets from the cams, then I din't see any reason for him to even expose the back end aligning slots - just sync the marks.

However, if he DID remove the sprockets and needed to reference the back end slots to get it back in time, then I do have a question: If the slots are parallel, with the intake slot above center line and exhaust slot below center line, my assumtion has been that all three timing marks should be aligned on the "safe" mark (not actual TDC). Is that correct? In other words, the entire timing process, starting from scratch, is performed in "safe" zone rather than TDC, allowing the cams to be spun with carefree abandon. Am I on the right page?

I'm trying to learn as much as I can about these engines before Volvo goes to the next version.

Chris

Your assumptions are correct, with one important condition; the crank needs to be positioned below TDC as step 1. THEN is would be safe to install the cam holder or, if the engine is assembled, turn the cams safely.

If somebody was to assume that the cams are timed for TDC, probed number 1 spark plug hole to position the crank, and then tightened down the cam holder... they'd be pushing #1 exhaust valve to nearly maximum lift while the piston is at maximum rise. And if the intake cam was mispositioned, it would be really easy to bend the valve not realizing the interference while tightening all those M7 bolts.

I agree that if the sprockets were not removed AND they were spot on in the first place, and the marks are visible (many stories on the board regarding missing timing marks) then no need to use the slots in back.

"...Your assumptions are correct, with one important condition; the crank needs to be positioned below TDC as step 1..."

So if the crank sprocket was aligned with it's well-advertised timing mark, that WOULD position all pistons slightly below the tops of their strokes (safe zone) rather than TDC, right?

Yes, that is correct.
Marks align to avoid piston and valve interference.

I am NOT using the cam locking tool. Just laying the aligned cams onto top of lower head and then SLOWLY 1/4 turn tighten the billion cover bolts from inside to out.
Keeping close eye for no cam rotation.

Rob

And the last thing that was a pain was removing the older anaerobic gasket material. I used Gasket remover from permatex, let it soak. Using long blade scraper....do not scratch/gouge surface. Repeat.

Rob

If you do another 20 valves, use a wooden or plastic scraper to get the glue off. You don't live in the 'snow belt', but a window ice scraper works real good.

To the above posts:

The crank timing mark does NOT put any piston at TDC. Aligning all 3 timing marks sets the stage for #1 to be fired first. If we were to use BTDC, there are some that would want to know how many degrees BTDC and that is not relevent when installing the cams.
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My name is Klaus and I am a V♂lv♂holic

I stand corrected. The #1 at TDC has no bearing as to exhaust or intake, that is up to the cams. While it takes 2 revolutions to get the cylinder in the compression stage, all 5 pistons move in the same manner.

So... align the crank mark on the pulley and glue down the cam cover.

When the cams go on, that will determine intake/exhaust cycle for the piston.

Make sure to rotate the crank 720 degrees after the belt is on and before the plugs go in. That will let you also check that the belt is on straight while checking the timing marks.

Have fun!

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My name is Klaus and I am a V♂lv♂holic

"...I stand corrected. The #1 at TDC has no bearing as to exhaust or intake, that is up to the cams...."

Now I must say this is a rarity. When I saw your first response I thought to myself "Wait a minute, that's not right. TDC is TDC until the crank is tied to the cams. But how do I respond? If I tell Klaus and Bob it makes no difference, what if I'm wrong? What if Bob lunches his engine because of me?"

So glad to see the correction. I slept much better.

There are quite a few times when a 'brain freeze' happens. And when it does, I expect others to jump right in and set the situation right or at least question my bungled answer.

I am just a novice shade tree mechanic.
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My name is Klaus and I am a V♂lv♂holic

Thanks for the support. I knew it was that simple!

As far a sealant I was going to use the permatex anaerobic sealant, but a lot of folks say bite the cost and use the Volvo OEM stuff.
I will use the Volvo stuff.

With all my effort, time and labor, I don't cheap on parts.

If you need any advise on R&R valve oil seals with head on, ask me.

Should be cranking up by Wednesday.

Best Rob

Of course we want to know all of the gorry details! Did you rent a valve spring compressor? Where did you get the 20 seals? Were the exhaust valve seals have more wear than the intake?

BTW, someone is looking for a cam cover tool to lock down the cover. He is in Canada/Buffalo area and willing to pay postage.
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My name is Klaus and I am a V♂lv♂holic

I bought the tool, cheap enough and I always find Volvo's for cheap to work on. Won't be long before a BLUE SMOKING 850 failed smog is on Craigslist for $500.

I get most of my parts from Pelicanparts.com since they are near be in the Bay Area. Or IPDUSA in Oregon or Autohausaz in AZ.

All the seals looked all worn, hard and tough to get off. A paint can opener also helped!

The compressor is the key! If I was going to do it again, I would tie a harness from the roof trusses and suspend my self.

The big helped is to put a cheeter bar on the valve compression tool handle to easy the leverage. I also had the front on ramps....I am 6'4"

Regards to all

Perhaps an old diving board suspended over the bay? I know what you mean, it took a few days for my back to straighten out just doing the oil separator - I'm 6' 7".

Thanks for the future help!
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My name is Klaus and I am a V♂lv♂holic

"...If you need any advise on R&R valve oil seals with head on, ask me..."

How about writing it up and posting your experiences to help guide others later down the road? Wish we had a FWD FAQ like Steve Ringlee created for the 700/900's.

As for me, I'm still pretty green in this white block world - got drug over here kicking and screaming after 30 years of red block RWD's. I'm just now starting to drink the Koolaid.

I have been pleasantly happy so far with the white blocks.
It is funny, now I only would buy one vs the reds.
Better mileage and newer style. And I really know my way around these cars now.
I think the 95 is the best year for DIYers.

I have redone the (3)PCV system rebuilds, (1)turbo rebuild, (4)ABS unit rebuilds, (2) T belts changes, water pump and all the typical tune up stuff. All Vac lines job too.

The bad is little less leg room and no rain gutters....had to get newer style racks!

Best
Rob

Don't know if this is proper but these resources are great:
http://www.matthewsvolvosite.com/volvo-850-repairs.

This is the one I used
http://www.matthewsvolvosite.com/plan-for-in-car-valve-stem-seals-replacement.html


https://sites.google.com/site/incarvalvestemsealreplacement/


My learnings are:
1. Use a compressor with spark plug adapter. (not the rope trick) Comes with tool below.
2. Get the universal valve tool. Lessor expensive ones can be found on Amazon. CTA 2235 worked great.
3. This tool will be used pushing handle with cheater bar, up on exhaust valves and then down on the intake ones. Not enough clearance at fire wall to push down.
3. To free the keepers from top spring plats, tap the plate with drift 1st to free them up. If not, the valve keepers will not break free when compressed and the valve with go down and releasing compressed air.
4. Take your time, your back will be stressed.
5. Use a flat head driver magnetized to help keep those keepers on. I always put them on from the passenger side, and then slid them around the stem to do the next one.
6. Get a seal puller! I used a surgical clamp pliers. Wiggle the seals and slower they pop off. Some bits may break off, go slow.
7. COVER all HOLES!!!! I lost one keeper but fished it out with magnet antenna. My heart stopped!!!!!!

Rob

People cross-reference the various repair forums all the time.

I was thinking that replacing all those seals must be a real back breaker. Maybe we could take a lesson from these guys:

http://bse.wisc.edu/hfhp/tipsheets_pdf/BERlaydown4web.pdf