I'm getting closer to having a good running engine (B20F). New manifold gasket made wonders and I've also adjusted the valves. Two jobs still left are ignition timing and flow testing of fuel injectors. I'd also like to do some checks on the FI system, but given the engine runs and starts OK, I figure it must be in reasonable working order. Now that the engine is idling smoother, I notice "rattling" and ticking sounds from within the engine. Odometer says 128,000, but it doesn't work so engine might have twice the mileage for all I know. Could anyone venture to suggest what are the most typical noises coming from an old engine and whether these jobs can be done with the engine in the car. I'm getting mentally prepared to do a complete rebuild, but I was hoping I could squeeze a few more miles out of it first. The engine burns about a quarter of oil for every 700 miles or so, but has no external leaks.

Thanks,
Kåre L

In increasing order of severity:

1) Look for loose components rattling on the engine. Loose brackets, busted motor mounts, etc.

2) Valve train clatter - loose valves tap tap tap (a fairly light weight noise) a little louder than normal. Usually valves tend to tightten slightly over time given plenty of neglect, however. And tight valves burn themselves. So an unusual lack of clicking is actually a warning sign. Adjusting the valves is about a 15 - 20 minute operation.

3) Funny business with the cam gear. The gears wear out. The fiber outer sections become separated from the steel hub. The brass thrust washer weare giving it fore/aft slack. All these can lead to a fairly noisy diesel-like clatter that can sound quite serious. Could be mistaken for a rod knock, but it usually goes away at higher rpms as the oil pump puts the camshaft under a constant pull. At lower RPM's the valves can shoot the cam forward as the lobe passes TDC - the resulting back and forth torque puts any slack in play. Luckily cam gears can be replaced with the engine in the car (probably worth the while to pull the radiator for room, however). Cams (worn lobes are depressingly common on high mileage B18/20 engines) can be replaced in situ as well, but you need to pull the head to remove the lifters. You should always use new lifters with a new cam, unless you happen to enjoy swapping cams.

4) Bottom end problems. As serious as it gets - worn rod or main bearings will clunk with a very heavy hefty sound. Bearing knocks like this can usually be diagnosed from a cam gear noise by when they occur. Cam noises are worst at idle, and fade as the revs increase. Rod and main clunks can occur at higher rpms, and are worst when the engine is slowing down (on the overrun). Rev the engine up, then close the throttle quickly and it will rattle worst as the engine slow down. Also the pistons can become a little loose on their wrist pins and slap against the head. Full rebuilds are the only way to cure these sorts of maladies, although used car salesmen sometimes find gear oil works wonders too...

Thanks, John - That was an excellent list. I don't think I have any bottom end problems, but all else could apply.
The only thing on your list I take exception to is the 15-20 min for a valve adjustment. Not if it's the first time :(

Kåre

Also may I suggest a bad fan clutch. Sounds more rattle-y than clunk-y. Easy way to check is take the fan belt off and go for a drive. Make it a short one as your water pump won't be doing anything, neither is your alternator.
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Justin 66 122E, 71 145S
Read vclassics!

You could also check the alt. bolts. A loose lower one will make a buzzing-rattle noise. Tighten them before you have to drill![don't ask me how I know!]



Mike M.

Thanks for the tip. I've had the alternator off several times already, so I know the bolts are OK. I had the lower bolt break off of my '75 242 B20 many years ago, but fortunately it was from a repair done at a Volvo shop and they fixed it at no charge. Makes you go "a-ha" when you see newer alternator lower mounts are attached both front and back.

Kåre