Hydraulic Tappets, Volvo 960

This is not an extremely complex job but it is a long detail intense procedure requiring special tools if little mechanical experience is the case, whether the cause be lifters or valves not sealing properly.

Hello

Many thanks for your advice

Do you believe the problem is caused by the hydraulic tappets or could there be some other reason for the big reduction in pressure when the engine is hot.

The strange thing is that the car runs very well. I have used the car for a year and it starts at the first turn, no smoke, powerfull, and good acceleration. People comment that the engine sounds very good.

My only complaint is the fuel consumption is high and the plugs foul up.

Following previous advice I replaced the external O rings on the injectors and made the joints on the air inlet more airtight and this helped the economy a lot.

The car had one previous owner, the interior and body are like new, but it was parked up for about 8 years before I bought it, and has done 120 thousand Km. The owner is given a new car by his employer every 4 years and keeps his earlier cars.

When I changed the oil it was very dirty and black

Any suggestions would be appreciated

Hi PotA,

Sounds rather like over-fuelling. The plug fouling and heavy fuel consumption(all Volvos of that era were thirsty ) are suggestive of too much juice going in. As this is all done by the engine management system you have some problems unless you have access to an engine diagnostic unit. However before you do that there are several sensors which should be checked for being in place and wiring not broken. The key one I think seeing how it starts up OK is the engine water temperature sensor which will be found somewhere around the head. If this fails ,by going cpen circuit,the system thinks the engine is always cold and keeps it on an over-rich mixture hence the mucky plugs and rapid build up of 'black' in the sump oil.

Beyond this check you may look for the lamda sensor on the exhaust down pipe to see if its still there,again the engine will run with a duff one but the mixture will be wrong.

Good luck,

Massey.

Hello pota,

Massey 726 gives you good information, and you may find this very interesting regarding reading the codes of Volvo without an OBD reader or software.

If you have never done it before you are in for a rough go! that job is slow moving with long detailed procedures and a need for special tools. I suggest you do not attempt it yourself unless you are an experienced mechanic, too many ways to mess up that will cost you time and big money to back up and replace!

I would add a top grade "Friction Proof" to the engine Oil. You should notice an Increase in the Smoothing Out of Engine Running as it Warms Up, and It will likely Be Noticable in a Drop in Oil Consumtion aswell.