I drove the 760t 257 miles yesterday - freeways and main roads. The last 45 miles the car was much weaker in power, the idle was not as smooth, and the motor was not near as quiet. Is this motor just old?

It is supposed to have only 140K on the car - which is low. I am having doubts this is accurate.

Any ideas? It is a B230FT.
--
'Be blessed in your quest'' 89 764 (110K), '94 940T (180K)

Thanks for all the input.

I still have a few things to work out - but the removing of the partially plugged cat went a long way to taking care of poor running. She ran fine all day, and did not lose power. In fact - on the freeway - I looked at the speedo and it was hard to keep her under 80. The B230FT really likes to run - that be for sure!

Thanks again.
--
'Be blessed in your quest'' 89 764 (110K), '94 940T (180K)

Take a look at timing: your knock sensor may have a problem. These symptoms are consistent with a drift in timing.
--
See the 700/900 FAQ under 'Select Link' button on the top right.

I will look at that closer. I did read in the FAQ's about the knock sensor and it's symptoms. Two mechanics - one of them supposedly an older series Volvo specialist - did not put too much stock in my suggestion that I might have a bad knock sensor. The tech at the dealership said he checked it. I will double check that check - to see if he really did it.

Actually - a lot of what I am experiencing did not take place until the distributor went bad - it ran pretty hot - I had the dist replaced, t Belt, seals, etc.
I think my next step is to straight pipe the catalytic converter - as it is rattling really bad. Then I will look to the knock sensor and timing.

Thanks
--
'Be blessed in your quest'' 89 764 (110K), '94 940T (180K)

I think you may be on to something by replacint the cat. Exhaust through put will be minimized if the cat is partially clogged and slow you down, a lot.

Klaus
--
(1975 164, 1995 854T, 1998 V70R)

And it'd also increase back-pressure to the point that a very minor leak at the manifold or the flange would become a very loud ticking.
--
Chris, Dartmouth NS Canada 70 M-B 280SE, 83 245DL, 84 244 turbo, 90 780 turbo, 92 VW Golf, 90 740 Rex/Regina

In what way is the motor "not as quiet" ? Could have manifold leak. How old is the timing belt? Could it have jumped a tooth? Check for loose/leaking intake system. Dirty gas/air filter? Bad gas tank pre-pump?

OK ..thanks for the reply. This may be a bit long, but I hope it helps someone come up with other ideas..

Just had a new t belt, front seals, plugs and replaced the water pump gaskets. Then I took it to a local Volvo dealership (good tech there for older bricks)- he troubleshooted some areas - and said that the intank pump was working. He found a wire out of place on the Idle Control Valve under the manifold - now it idles better. Oh - had a new fuel filter and check valve installed a few months back.

I had not considered a exhaust leak, but that may be the sound that I hear at times. I had thought the sound was from an overworked front fuel pump (which led me to questioning the in - tank pump) or something loose in the motor. It is a steady low pitched tap, and it is not there all the time or as strong as other times.

Clue? When I was coming in yeterday the tap was very noticible - along with reduced power.

By the way - this morning - she is running better - valves still a bit noisey. The valves sound like some 240's I have drove with really high mileage. I will check the exhaust gaskets.
--
'Be blessed in your quest'' 89 764 (110K), '94 940T (180K)

CJ - that is almost what it sounds like. I know the valves are really noisy at the end of the day. Not at the start of the day, mind you. As I said in the reply to Steve - I am going to straight pipe the cat - remove that noise - and go from there.

Do you have any suggestions for a sticking valve - other than a valve job. That might be where I am headed.

Thanks
--
'Be blessed in your quest'' 89 764 (110K), '94 940T (180K)

Well the first question is why is it sticking, if indeed it is. Any sign of overheating? Has the car been subjected to cheap oil that's coked up on the valve stems? I've seen carbon deposits from cheap gas wreak havoc on a couple of 850 valvetrains, and if you're a particularly pedestrian driver (ie, never over 3500rpm) that driving style doesn't do the engine any good. I know of mechanics who swear by various fuel additives for carbon removal. Also do a search here for info on seafoam treatment (both pros and cons). Switching to good-quality synth oil like Mobil 1 will gradually help clean up carbon deposits including in the valve guides. If possible do a compression test when the engine is acting up to verify if it's indeed a sticking valve, you should have lower compression in the offending cylinder. That would explain the ticking, as the cam lobe hammers against the partially-depressed follower instead of gliding across it, as well as power loss.
--
Chris, Dartmouth NS Canada 70 M-B 280SE, 83 245DL, 84 244 turbo, 90 780 turbo, 92 VW Golf, 90 740 Rex/Regina

CJ..I think that you may have hit on it. I will do the cat bypass asap - and then look to a possible stuck valve. As for overheating - I do not know if the PO had this happen, but it would not surprise me. It got pretty hot on me when the distributor messed up and I drove it a few blocks in retard mode - but I would not classify that as overheating. The valves would have really been working out of time to an extreme amount though. That may have had the effect of revealing a carbon problem from before.

There is a process I might look to using water and an additive that I have read about. It is supposed to really clean the top end but needs to be used carefully. Do you recall the name / process? Or do you have another recommendaion?

Thanks all.
--
'Be blessed in your quest'' 89 764 (110K), '94 940T (180K)

http://www.brickboard.com/FAQ/700-900/EngineMechanical.htm#CombustionChamberDepositRemoval

This is the technique I used. Don't let it stall out. Do the procedure exact. Take your time. After, full flametrap cleaning, and oil and filter change. Quieted my motor down alot. BTW, I used the flametrap vacuum hose that plugs into the inboard side of the manifold.

Thanks - Cat.
--
'Be blessed in your quest'' 89 764 (110K), '94 940T (180K)