I recently completed removal and replacement of the cylinder head on my 97 V90 due to 17 bent valves after a timing belt failure at 70 mph caused by a seized idler. What a job it was, a few hitches here and there but it's complete and engine is running great.
During the course of the job 2 questions came up that have me very curious.

1.
The pulsed air injection system whose purpose is to flow air into the exhaust system for a minute or so on cold start ups feeds into a passageway on the top of the upper head under the plastic coil cover. How does this passage feed into the exhaust?

2.
There was no rear camshaft seal installed at the rear of the intake cam when I disassembled. Upon talking to a seasoned Volvo indy mechanic he said that he seemed to remember the same thing. I did not install a seal even though the head and upper head are machined to accept a seal. Of course I did install a new seal on the rear of the exhaust camshaft as well as 2 seals on the front. There is only a push in plastic dust cover over the opening where the "missing" seal would be. There was no sign of any oil leakage before or after the job. I thought this strange.

Any thoughts????

1. There is a passage way between the port where the pipe connects and the exhaust in the middle. The extra air is used at the CAT so the actual exhaust port doesn't mater.

2. There is no moving lip seal on the back of the intake cam. The cover has a seal around it's edge. I think my new cover was black painted metal with a rubber seal bonded around the edge. I had to devise a tool, (plate with appropriate holes) to pull it into place using screws in the taped holes around the opening. Some of the same ones used for the connector bracket for the cam sensor etc. It was too tight to push into place by hand.

It is good to hear that you recovered by just replacing valves.
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'96 965, 16' wheels, Michelin Pilot Sports, rear 18mm bar + Koni, 201 HP cams, 133K. Put 200K on '85 745 TD.

I guess the paasageway to the exhaust is internal through the head and connecting to the exhaust in the #3 or 4 passageway between the valves and the actual connection to the manifold.

I pushed the plastic cover into place with a bit of sealant around the edge. The metal plate for the wire connectors goes over that cover and would prevent it from ever coming out.

Yes the only damage was the valves. I talked to a seasoned indy Volvo mechanic who has done the job many times, he said that he has never seen or heard of any other damage except to the valves when the timing belt fails.
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David Hunter

The first time I cracked open the head on my engine, it too was missing the rear intake cam seal. I did have the dealer replace the lifters under warranty and thought at the time that the dealer was just being lazy. There was some sealant around the plastic end cap. But if your head was original, then maybe I will have to revise my opinion of the dealer. No, I guess I cannot do that, they never ever figured out that the engine held six quarts of oil at an oil change, even when I reminded them when dropping off the car.
Do not know anything about the EGR system, as my '94 has none of that equipment.

DanR 94 964 300,000 miles (66,000 on the new engine)
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DanR

Thanks for the response, I guess your experience confirms what I thought. The intake cam could potentially pass oil thorough the rear cam journal bearing but it would actually drain down back to the crankcase before reaching the plastic seal. I guess they just thought a seal was not needed there.

The pulsed air injection is not actually EGR it is a system that injects fresh air into the exhaust when cold to speed up the chemical reaction and heating up of the cat. I think it started in 96, one of those things to keep the greenies, California, Al Gore and others of his ilk happy.
David Hunter