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Hi!
I’ll try to be as specific as possible.
Got a 1986-model Volvo 740 Turbo Intercooler. Engine type is B230ET (2.3 liter turbocharged, electronic (Motronic 1.0) fuel injection) and transmission M46 (4-speed manual with overdrive). This car were sold in Norway new, not imported. Since it is older than 1989, it does not have a catalytic converter. Bought it in 2012. This is a car I care very much for and do the best I can to maintain. I also always fill it with 98 octane fuel (93 or so in the US), as specified in the manual. When driving, I never go past 3000 RPM, or use the turbocharger, before it is at full operating temperature.
The engine was at a full rebuild/overhaul for 1,5 years ago, or about 20.000km/12.000 miles ago. This was done at a professional engine workshop. The exact milage before the rebuild is unknown. The speedometer have been manipulated at some point. It did read approximately 220.000km (136.000 miles), but paperwork from the official vehicle authorities suggest it in reality is twice the milage. The engine did have poor compression in one sylinder and several leaks. Thought it was time to get it rebuilt. After I got the car back, I had a tapping sound coming from the engine. I filmed it to capture the sound when I start the car, see link below. You can hear it really well before I open the hood. It does follow the RPM.
I were told it is harmless and just the valves that needed adjustment. I were recommended to not do the adjustment right after the engine rebuild as the parts were seating. Doing it early I would just end up with the same sound again because the parts would not be fully seated. The valves in this engine apparently is of a special type that only the dealership can adjust. I’ve done it twice since the rebuild, but still have the same tapping sounds. It was not like that before the engine rebuild. I am concerned about this noise. No one seems to really care about looking into it or fix it. I’ve been to several workshops, but every time it is either the valves, just harmless/normal or simply “it is an old car, after all”.
I’ve been very precise with the oil changes. I change the oil every 10.000km or 6 months, whichever comes first. The user manual says the same thing too. I always use OEM oil filters. After I got the car back from the rebuild I were told to change the oil after 500km, then 1500km after that, which I did. After that I’ve changed the oil as specified in the manual. I’ve used the exact same oil that the rebuild workshop used and recommend, Castrol Magnatec C3 5W-40 (synthetic). I always check the level once a week, and it has been consistent. Never had to top it up. The manual doesn’t state a specific type of oil, it just shows a chart with different oil types. You can see it in the picture below.
Is this something I should be concerned about? Any suggestions to what this is? If it is the valves, can this be fixed with regular tools in my own garage? At this point I don’t really trust the workshops that say that they cannot adjust the valves because they’re special…
http://www.youtube.com/watch?v=RjIHGwojPkk
[URL=http://s1218.photobucket.com/user/frankbilder/media/olje_zps2axkmpkh.jpg.html][IMG]http://i1218.photobucket.com/albums/dd414/frankbilder/olje_zps2axkmpkh.jpg[/IMG][/URL]
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Replies
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Could be coincidence, or maybe you’re leaking combustion pressure into the coolant.
As for the piston slap, I’m not convinced. Doesn’t really sound like classic piston slap, but I could be wrong. If you really are running undersized pistons and rings, you would be experiencing high oil consumption and obvious signs of blow by.
Yes, I would think it would have oil consumption and such, but it doesn’t. It did use oil the first year or so, but only because it were leaking past all gaskets/seals while they settled in. Had to top it up maybe once before the next oil change. The engine looks like a mess and I probably should degrease and clean it a bit for aesthetic purposes. Half a year ago or so, it stopped. The oil level stays the same. The vacuum is better after the rebuild, compression is good and all that. Just that annoying noise…
I guess the coolant issue is just a pure coincidence and bad luck. If combustion pressure is leaking into the cooling system, then the coolant should be contaminated? Haven’t ever seen any evidence of contamination, nor any abnormal fumes from the exhaust that would indicate coolant leaking into the combustion chamber.
Finally got my car back from repair after the core plug incident. They also found that the gasket for the thermostat housing were faulty, which could explain the minor coolant loss I were experiencing earlier. They were concerned that the engine might’ve suffered serious damage since I have potentially driven the car 6km (4-ish miles) before I stopped. Everything checked out good, so no damage done thankfully.
Anyhow, on to the main topic regarding the tapping noise. The workshop pulled out and checked the shaft and found no significant wear, not really worn at all. They double checked that the flame arrestor/crank case ventilation doohickey is the correct part, which it was. It was also found that the valves were really loose, so those got adjusted. Guess the dealership actually didn’t adjust the valves then, 600 bucks well spent… Several people had looked into the noise while troubleshooting. No one could figure out the cause. However, the engine is a lot more quiet now after the valve adjustment. Quiet enough so that people don’t rise an eyebrow when the engine is running. There are still some of the tapping noise left, but it disappears once the engine start to warm up.
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