The engine was overhauled a few months ago, has around 100 hrs on the overhaul. Operator said they noticed a slight ticking noise. Pulled the valve cover the next day and to my surprise. There were 8 broken outer exhaust valve springs! Luckily the inner spring was still holding them in place. The head was gone through by a reputable machine shop and they did replace all the springs at the time. What would cause something like this? Just a bad batch of springs or is there something else I’m missing. It wasn’t over-revved that I know of. No codes for it. We are pulling the head and they are going to make it right but I want to see if anyone else ran into something like this. The cam was the original cam and the rockers, rocker shafts, and bridges were all replaced with new from Volvo.
If your valve lash is set too tight can the springs coil bind perhaps? Coilbinding a spring will certainly cause issues.
I believe that there was an updated valve spring for the 13 and 16 liter engines. Do you have the I-EGR double rockers on the exhaust? If so, do you have the tools for adjusting the hook end.As zlssefi mentioned, the adjustment could be incorrect. You may want to consult with the dealer in your area regarding the updated springs.Thank goodness none of the valves got eaten. Good luck.
It does have the I-EGR double rockers. The procedure was followed by the book when the overhead was done. I will check into see if there were updates.
Why were the rocker arms replaced, what style valve bridges are you running, the T-shaped ones that run on a pin or the floating ones. The ones on pins require a different spring because the pin bracket sits under the spring acting like a shim. The update I mentioned goes back 7 or 8 years ago and was fix as failed, iirc.
Rockers and shaft were replaced during the overhaul because of wear from dust contamination. (Motor was dusted which is why it was overhauled) It has the T style bridges with the pin. Do you have any reference numbers to any bulletins by chance?
No, i sure don't. You'll have to ask service as parts may not be "on the ball" By the way, the floating bridge is the preferred.
Here are a few pictures of the damage. Luckily the valves stayed in place and everything looks good piston/block-wise. My dealer did provide a few bulletins for valve springs. I’ll have to find out what the head rebuilder used.
Ok, you have the improved I-EGR arms with 4 lobes per cylinder. You need to take the slave piston out of the EGR arm, inspect that spanner plunger , make sure it has not backed off. You will see what I'm talking about. I would strongly recommend taking each one out, clean, disassemble, dry , reassemble with bearing and sleeve mount and piene the threads to prevent backing off.
I did have the pistons out of them today to take a look at them. Mostly paying attention to the bores and the part that contacts the bridge. Are you saying disassemble the piston assembly after you pull them from the rocker? Or check the one the smaller arm contacts. You can see part of it in This picture.
There's a piston that wants to fall out the bottom of the rocker. The adjust screw impinges directly onto this piston. That piston has a spanner cap on it. That's what you gotta check. Have had them loosen up and suddenly take up all the lash.
Okay I did see the holes on the top of the pistons where you could put say the pins of a spanner wrench. I’ll pull them out and make sure they didn’t loosen up for some reason. That would make sense if they did loosen and you would loose your lash.
Here are the backside of those pistons. They all appear to be in good shape and haven’t loosened. You can see the factory peen/spot weld marks.
Terrific, that's an improvement i haven't seen. Sorry for asking you to do something unnecessary. Had to rule it out as a possibility. Let's see what parts bulletins shows against what your rebuilder used.
I haven't messed with engines in years just because of things like this. Who knows how many updates and "improvements" have come about since an engine was manufactured and then rebuilt years later. Parts people can be your worst enemy on these things and manufacturers tend to not want obsolete stock back which forces the dealerships to wan to sell the old stuff out. Many service departments also hold service news and update warnings close to the vest as well if they thing someone is stealing "their" business.