96 850 Turbo Wagon Mechanic's Challenge

[FlipIt]

I removed the distributor and the camshaft position sensor to check the camshaft timing slots. The axis of the camshafts is below the top of the fenders so it is very difficult the check the alignment visually. I tried taking a photo with my camera in line with the axis of the camshaft but it is time consuming and inconvenient to transfer the photo from the camera to the computer to view the image.

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I must admit that I rather enjoy working on this engine even though working thru the wheel well is awkward. I believe the last DOHC engine I worked on was my 1964 Alfa Romeo 2600 Spider many years ago. From watching Craig's list blown head gaskets seems fairly common on the 850s. Because of the extensive labor and special tools required to replace a head gasket it is not economical to spend $1500 repairing a vehicle only worth $2,500 to $4,000. So I'll probably buy another one of these in the future.

Below is a photo I found on the internet of a Volvo camshaft alignment tool.

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I decided to fabricate something similar from aluminum angle stock, nuts and bolts.

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Here it is in use.

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The tool is not strong enough to actually align the cams. It only serves as a visual reference. The 1/8 inch thick aluminum is less than the thickness of the cam slots so the tool is pushed downward on the intake cam and upward on the exhaust cam. using the tool I believe I was able to align the cams accurate to 1 or 2 degrees.

[boosted5cyl]

Looks like you are well on your way. Does it look like the cams were aligned correctly? People seem to be afriad of these cars, but if you take a little time to get to know them they can be pretty rewarding IMO.

I made a ghetto cam lock out of mild steel. It was fine for the alignment, but when I had to torque the center cam spricket bolt to 88ft\lbs things went a little pear shaped. I might make another one and try and temper it. The 850 doesnt have VVT so no worries there.

[FlipIt]

The intake camshaft required no adjustment but the exhaust camshaft was a few degrees off which I corrected.

I bought a new group 47 battery with 590 CCA at WalMart. When I removed the old dead battery I found a vacuum hose underneath it.

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I suspect this is the hose that connects to the cruise control vacuum pump. Does anyone know where the vacuum pump is supposed to be mounted?

I wired the throttle plate open in preparation for performing compression testing. There was considerable linkage binding at the mid-throttle position and the linkage prevents the throttle plate from reaching WOT.

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I'll work on the linkage after I get the engine running.

With all the plugs out I noticed that it took more than 35 ft-lbs to rotate the crankshaft. Since the cylinder walls could be rusted from sitting for so long I added 3 squirts of engine oil to each cylinder thru the spark plug holes. I cranked the engine with my torque wrench until the required torque dropped to less than 25 ft-lbs. Then I started compression testing using the starter motor. The more I cranked the engine the better the compression got until all cylinders were above 150 psi. Since the specified compression limits are 156 to 185 psi I added some more squirts of oil to each cylinder. When I tested cylinder #5 the compression dropped to 75 psi. I guess its possible that I added too much oil and blew the head gasket but the gauge should have indicated a high reading. Other possibilities are a broken compression ring, a broken valve spring or a sticking valve. After thinking it over some I've decided to assemble the engine enough to crank it with spark and fuel. Even with one bad cylinder the engine should start and run. After it runs a little I'll check the compression again to see if anything has changed. I don't want to pull the head until after the engine runs. I may find other things that need repair/replacement from the OBD-II diagnostics.

[Klausc]

The vacuum pump is mounted to the bottom of the battery tray. My purple vacuum line is not routed through the hole but around the tray to the pump.
There is a battery hold-down wedge, probably missing, you can get at the dealer cheaply enough.
When you figure out the binding on the throttle, I would be interested because my throttle is getting hard to push. I am waiting until spring (warmth) before I open up the throttle body and inspect everything.

As to your compression readings, they need to be taken with a warm engine to be valid. Rings usually last forever in these cars, valves on the otherhand have a problem because the rpms need to be over 2K before the valves spin during operation. It could be a bad valve or just really dirty. The extra heat from a bad exhaust valve could have been the initial problem for the blown head gasket.

You are doing very well, keep having fun.

[FlipIt]

Thanks Klausc on where the vacuum pump mounts. The hose for it was pressed flat from the weight of the battery. One of the vacuum ports on the pump is broken off so I bought one on eBay. I have already received it. There's nothing wedge shaped in my box of parts so I'll have to acquire a battery stop.

I'm trying to reroute wiring and hoses in a way that seems reasonable but it's hard without something to refer to. The hose from the radiator lower port to the rear of the engine bay is obviously routed incorrectly and eventually would have been punctured by the bracket for the camshaft position sensor connector. The wire loom for the injectors is shot but the wiring still looks good. The copper Autolite spark plugs are the correct heat range according to Autolite's table but are gapped at .045 inches. The owner's manual specifies Champion RC7GYC at .028 inches for the turbo. I checked the Champion website and they no longer manufacture that plug. Three of the plugs have cracked insulators. I'll buy new plugs tomorrow. Any suggestions?

[Ozark Lee]

I use the Bosch Coppers for plugs - I would give you the plug number but they changed the numbering system last year and the new number isn't top of mind. They are dirt cheap but they typically come out of the box at about 0.035 to 0.040. Gap them at 0.028 or even slightly less and they run great.

The downside is that they only last 20 to 30 k miles but they are so cheap that it falls into the "who cares" category.

...Lee

[Klausc]

I used a length of large diameter vacuum line to wrap the injector wires. I don't know what Volvo was thinking with that brittle plastic stuff. I use the expensive Volvo plugs, they last a good 50K miles in a turbo.

The intercooler line from the turbo, up over the engine and down to the bottom of the radiator looks correct in the picture. Beware of the small vacuum lines that go to the turbo, it is important that they do not get confused.

Make a clean cut on the cruise vacuum line and suck on it. If you can build up vacuum, the throttle should move a little which means that the CC switch is still good.

The wires from the cam position sensor must not go near the distributer or plug wires, otherwise the computer will pick up false signals.

I wish my garage were above freezing so I could work on mine.

[anmartin44]

bosch coppers are "FR7DC" i believe

[Ozark Lee]

bosch coppers are "FR7DC" i believe

They were but Bosch changed the numbering - I think they are now a part number 7955 after a Google search. I can only find them at NAPA but they are under $2.00 each the last time I bought them.

...Lee

[FlipIt]

According to boschautoparts.com there is no OEM equivalent Bosch plug for an 96 850 turbo. The FR7DPP+ is listed for the 95 850 T-5R, the 97 850 T-5 and the 97 850 R all with the B5234T5 engine but there is no listing for the B5234T engine. My owner's manual lists the FR6DC for the B5252S (10.0:1) and the B5254S (10.5:1). I believe 7 is a hotter plug than 6 which is probably suitable for my 8.5:1 compression.