posted Mar 20, 2010, 7:07 PM by Mark Crimmins
updated Jul 6, 2014, 7:34 PM
The problem: 1996 Volvo 850, 160K miles, with high oil consumption, high hydrocarbons in the California smog test, and, in addition to general stinkiness, the dreaded blue cloud upon rev after 10-minute warm idle:
On the bright side, the garage smoke alarm works!
Diagnosis: either turbo seals (but I could feel no shaft-play in the turbo), or valve stem seals. It's cheap in terms of parts, but a lot of work, to replace the seals. A free weekend, and here we go.
It was also past time for a new timing belt, water pump, and upper engine torque bar bushing; so these will be covered here as well.
The steps for this job are listed in the post called "Step-by-Step Instructions" (click on "Home" over there on the left). Here I will explain how it went for me, and post pictures of the process. Click on the pictures for larger versions.
To remove the serpentine belt, you need to stick something in a 3/4 inch square opening on the tensioner and torque it. IPD sells a $30 (!) tool, someone online cobbled together a few plumbing parts to make one for half that, and an ebay entrepreneur sells a specially-fashioned insert, but seriously, this is not that hard! I cut a 5/8 inch length of 3/4 inch angle aluminum stock (about 1/8 inch thick), stuck it in the tensioner, and then a normal 1/2 inch socket wrench does the trick:
Even if you don't have the angle stock on hand, a couple of nickels or quarters would do fine. A nail in the tensioner hole locks it.
Got stuff out of the way for timing belt removal:
and the wheel well liner out of the way:
---later it would prove useful to remove another plastic nut and pull more of the liner out of the way. I used a 30mm socket on the crankshaft to line up the timing marks. The crank mark is very subtle:
It's that tiny notch at the back of the gear trough:
(you won't realize how hard it was to get that picture until you go in there), So I drew with my "metallic" Sharpie marker on that sprocket trough, to make that trough easier to see later:
Those are valve stem seal removal pliers---$12 on ebay; you'll see them again in a less original use. By the way, some of these cars have little notches on the two sprocket teeth surrounding the TDC position (you line the trough between them up with the mark).
Wriggled off the timing belt---surprisingly quickly, given the hand-wringing about it on the web (putting the new one on took longer). You have to finesse it past some sort of lump at the bottom where there's not much room between the lump and the pulley (what the heck is that lump there for?) ; you basically just want the belt flat against the back of the pulley so that it can squeeze past the lump. I transfered marks from the old onto the new belt, which made for much less guesswork installing the new belt:
Mark the intake sprocket so that you don't confuse them. Everyone seems to mark both. LOSERS, there are only two!
At this stage, I replaced the idler and tensioner pulleys, which are visible in the photo above. There is a silly Torx bolt holding the tensioner pulley on, with very tight clearance to get to it. I used a box-end wrench around the hex shaft of my Torx socket/bit (it turns out that that's the usual way, though be careful, people report stripping the Torx head), and a pipe on that for leverage:
Next I replaced the water pump. Be sure to get every last bit of the old gasket on the block mating surface; it's no fun to go in again after a leak---and it DOES happen. I put the new gasket on the block first:
and then just bolted the new pump on:
The old pump did have a tiny bit of bearing play and made a groaning noise, so at 160K miles this was probably a good call.
Removing the cam sprockets was not too hard. I used a strap wrench to hold the sprockets while loosening the bolts (which seemed way tighter than spec). In hindsight I would have waited to remove the sprockets until after I had taken off the rotor and cam sensor plates---the bolts on the camshafts at that end are tight enough that you have to hold the cams from rotating while removing them Never mind how I did that; keep the sprockets on for that bit.
Nice and dry at the front seals, anyway.
Now to the "rear" side of the engine. I removed the air filter housing to get room to work.
and the turbo pipe that goes over the engine. I'd seen the oil here before. It made me worry that my smoke/oil issues might really owe to the turbo rather than stem seals. But like I said, there is no shaft play in the turbo, so stem seals still seemed to be my best bet.
Some oozage at the exhast camshaft rear seal, but maybe not a lot:
The top cam sensor mounting Torx bolt was torqued in like it was an axle nut or something, and the lower one was about finger-tight. Dang those Swedes.
Here is where I took some sage online advice, and I do not hesitate to recommend it. The official line everywhere is to set up some locking devices to hold the camshafts in place and to keep them from rotating. Sage advice guy says there is no point to that. Just back off on the bolts gradually and be sure the upper cylinder head comes up evenly. No need at all for cam holders, locks, or head pullers (people weld old spark plugs to threaded rod, hacksaw angle-iron contraptions, etc., etc.). This appealed to my "don't do hard things" instinct, and so I tried it. Moreover, it worked. A couple of caveats. First, this doesn't let you "set timing" very easily, so I was limited to reinstalling the cam sprockets in the same position they had been installed in by whoever did the last timing belt job on my car (I relied on the bolt-wear marks). Second, you really really don't want to bend the top-half head, and you really really don't want to bind the camshafts in the head, so you do have to be careful. Also, sure, do not pry between mating surfaces. But I can't see how to avoid prying between the points that are obviously set up for prying between. I would suggest prying between such points. Back off the bolts an eighth of an inch at a time or so, and...
And soon the head is apart.
I stored the lifters upside-down, keeping track of where they go. I did not bathe them in oil. I don't see how they can lose oil upside-down, but I am not an old hand at this, and I only had them out for a day.
Nasty-looking sludge at the rear---just because there is no flow there, so oil sits and bakes, maybe?
The old camshaft seals. The rear intake (at the distributor) looked nasty, but there were no signs of leakage there.
Okay, so now to the business: replacing the valve stem seals. The Schley tool is great. Instead of using an air compressor (I don't have one) I shoved rope into the cylinders at their low point and cranked them tight. Just stick some plastic or wooden item longer than 6 inches (I used a big cable tie) in the cylinder to figure out when it's high or low (obviously never leave any material in a cylinder). I used about 8 feet of 1/4-inch diameter Home Depot poly-something-or-other rope. It takes some strength to use the compressor, and you'll be glad you spent time at the start making a good prop to hold the handle when the valve spring is sprung. I used a block of maple about 4 inches long. You compress (and prop), pry the keepers from the shaft with a small tool, extract them with a magnetized tool, uncompress, remove the spring, pull the old seal, install the new (I used a deep 11mm socket; takes zero force to install these things, by the way), compress (and prop), fiddle in the keepers, and uncompress.
"Fiddling in" is BY FAR the hardest part of this whole enterprise. My best strategy (which isn't saying much) is this: put a gob of grease on the slotted side of the keeper; hold it on the tip of a magnetized Torx screwdriver (you can magnetize it by drawing it across a magnet); position it near the shaft and use an unmagnetized tool (I used a wooden shish-kebab skewer) to try to push it into place. Pain. In. The. Butt. (The back, really; help yourself out and find a way to use old pillows or something to make working out across the engine bay less strenuous. I sure wish I had.) Try to find someone with a better fiddling idea! With a 20-valve engine, you only have 40 keepers to place :-)
The old seals were rock hard---chalky, as well as having no lip. Not seals anymore:
I started the new ones on the valve shafts by hand --- it looked like you could lose one into the nether regions, and I didn't want to risk that --- and then pressed them into place with the deep socket. Volvo supplies valve condoms, but I really don't see the point: these do not seem to be such delicate seals that you could harm them that way.
A couple of times the rope got pinched by a valve and I had to find the culprit valve by trial and error. I used the spring compressor, but you could probably use a rubber mallet.
Many hours later (just ask my back), I cleaned up the mating surfaces and positioned the camshafts on the engine; be sure you have marked the shafts so that you know the right orientation!!!: If you haven't, don't worry; you can figure it out by the offset slots on the rear ends of the shafts---both are horizontal, with the intake above the centerline, and the exhaust below.
Then I spread gasket compound on the cam cover (lightly!) and greased the bearing surfaces (the last time I used this particular tub of assembly grease was in the 80's for a Honda CB350 motorcycle . . . like the corners of my mind . . . ):
Reinstalled the lifters, positioned the upper head, and gradually tightened the zillion bolts, keeping an eye on evenness, including the rotation of the camshafts (mine didn't budge). Did I mention that my back hurts?
Put in the front seals with the help of one plumbing thingy:
Installed the cam sprockets, matching the marks left by the bolt-heads to ensure that I installed the sprockets at the original angle with respect to the shafts (there is by design considerable play in the sprocket bolt-holes).
Installed the new timing belt:
(OK, I did mark the exhaust sprocket. LOSER.)
A good trick is to back the crank off a notch, put on the belt, and tighten the crank back. That way you don't have to struggle to kep the belt taut between the intake sproket and the crank sprocket.
Installed the rear seals with another plumbing thingy (I wandered around Home Depot with a caliper: just under 2.25 inches for the front, and just under 1 7/8 inches for the rear):
And just as I read that my plan said "Install torque arm brackets", at that exact moment, the mail carrier arrived with a brand new torque arm bracket bushing from FCP Groton. Yay for their fast shipping! (The package also included 75-cent spark plug o-rings, but I had broken down and paid $4.50 each for them at the dealer, making for probably a world record payment for some stupid o-rings, NASA aside.)
To get the old torque arm bushing out (the middle part was gone already, thanks to decrepitude), I did this (plugged the open intake pipes and vacuumed well afterwards):
Pushing in the new one, I used a C-clamp and some pieces of wood with 1-inch holes partway through them. Went swimmingly. Hey, since I did this I read that someone brilliantly put their bushing in the freezer to shrink it, which really eases installation (the only part that's at all tricky is starting the new bushing into the bracket, and apparently I was lucky, because sometimes it's nearly impossible to get it in there). The arrow on the bushing points at 11 o'clock--a little towards the front of the car.
That's about it. I took out the fuel pump fuse (#2) and the coil wire, cranked a few seconds a few times to get oil up there, and let it marinate. Then, I reconnected everything and put in the key. Surprisingly, it started right up. I drove around a bit to get it warm, idled for 10 minutes and ...
Four years and fifty five thousand miles later, the car is still running great, getting the same mileage as before, and the oil loss is dramatically reduced, despite the fact that the engine is clearly still leaking from the rear main seal. (Stay tuned for a write-up of that job...when I get around to actually doing that job.) The hydrocarbon emissions, measured two years after the job, are about half of what they were before the job, and are lower than they were when the car had 100K miles.
This job took 2 full days. I could get it down to one day, maybe
, given the experience. I'd never done a timing belt job on this car before, let alone the valve stem seals, so certainly I wasted some newbie time. But some parts of the job are simply time-consuming, like fiddling in 40 keepers, cleaning gasket material, and gradually loosening and tightening thirty-some bolts. And it's a back-breaker, so it may be unwise to do it all in one blast. So I'd plan to spend some time on this.
Within a few weeks of finishing, I sold the Schley compressor and stem seal wrench to another Volvo owner. So you needn't think of tool costs on this job as irrecoverable; as these cars get on in miles, this will become a more and more common procedure.
If you have anything to correct or to suggest about any of this, please leave your comment below, so that people who are thinking of doing this will see it. Thanks!
Added 7/25/2010: Here's some advice posted on VolvoSpeed from Gihuly, who did this job [and my comments between brackets],
The sprockets don't have to come off. I just take the whole thing out and put it all back in with seals already in place. When replacing seals they can be worked over the shaft into place. [Not the front seals, surely.]
1. This will fix a smoking at idle 850 which is not from a blown turbo (diagnose by much oil in intercooler), bad rings or bad valve guides. The valve seals looked to have been re-used in a cheap ebay rebuild ($300 rebuilt head last year).
2. I highly recommend this to be a two man job. There is plenty to keep two busy and operating the schley tool really should have a dedicated person. It was helpful when replacing keepers to be able to call, "half way up, no back down, up.....". We used 4 ft of cheater pipe on the schley handle and this made things much easier. [Great idea.]
3.Take your time on cam cover removal. This is the riskiest part of the job, IMO as you can crack the head where the shafts fit in.
4. Cover all the open holes, including the intercooler piping in back and handle the keepers over the head only. We still had two runaways, one dropped in the engine compartment and another made a break for it and shot out of the head and fell downon the cross member heat shield at bottom.
5. I highly recommend the compressor method for securing the valves using a spark plug hole fitting that can be purchased almost anywhere cheap. The rope trick for us was tricky and the rope got stuck I think 4 ways on the first cylinder. We switched afterward to air.
6. Special implements: I had a dental pick for helping free the keepers which was awesome and also for helping manipulate the keepers back in after seal replacement. Also for keeper replacement using a long slender screw driver and some thick grease gun grease. Put a very small amount of grease on the screwdriver tip and stick the keeper to it and put it in with dental pick or other tool in other hand. Also, have a small diameter telescoping magnet that will fit inside the schley tool for valve keeper retrieval.
Again, I really call this a two man job. We did it in a long day (11 hrs incl lunch). Other skills required are timing belt removal/replacement skills. TDC on #1, crank shaft gear mark lined up on the block and slots on the camshaft ends level with head suface, exhaust slot cheats below the centerline, intake cheats above.
It was very rewarding to take this car back from being a smoking embarassment (it was bad and came on almost immediately) to a fine runnning car again. [Exactly! And thanks for the feedback.]