Can anyone tell me what would cause 9 of the 12 intake valve springs to break? I replaced all 48 springs and adjusted everything including the Jake brake but the noise is still there. Help
First things first - Serial Number ........... Did you find the broken springs while looking for the knock or for some other reason..? Have you had the cylinder head off yet..?
2ks serial# yes I found them while looking for knock. head off all 48 springs replaced, head reinstalled valves and jakes adjusted .015intake .025exhaust .040jakes . didn't see any other broken parts but honestly thought the springs were the problem. No budget to do overhaul
How many miles on the engine and do you know any of the previous repair history..? Did the knock start suddenly or has it been building up for a while..? Any signs of the valves hitting the tops of the pistons because of the broken springs..? Did you replace the valve guides..?
there's about 300,000 on a previously rebuild ( so I was told) the knock started suddenly and the tops of the pistons showed no signs of any damage a little carbon but no signs of hitting the valves. I did not change the guides, the valve stems fit tight, there was no side to side movement. a couple of the valve seals ( shields) were broken/brittle. I also change the base plates / injector positioning. The oil gets change every 15,000 miles with 1 gallon of Lucus added. air filters changed twice a year. this is in a tri-axle dump truck on /off road applications every day
A weird one. However IMHO broken springs wouldn't cause a knock, despite the fact they are not really desirable. To get a knock something's either hitting somewhere or has far too much slop in it, small ends maybe..? Bottom end would surely show itself as low oil pressure. The only other thing I can think of would be a fuel knock - possible..?
My guess is something to do with the Jake brakes. When I worked on trucks I used to see plenty of bent push rods because the Jakes were set or got too loose. I'm also wondering if the driver was shifting gears with the Jakes on. Seen a few dropped valves on one truck and it was theorized the driver would drop engine RPM on the Jakes and miss a shift going completely into gear and over revved the engine. New driver on that truck and the problem never showed up again. Could also be tired springs.
Have you inspected the camshaft and followers yet?
just removed head again, found two worn journals. can you tell me how to get the cam out?
Here's the short version. PM me with your email address if you want something full-blown with photos. Note: It is not necessary to remove the cylinder head for removal of the camshaft. Start By: Remove the rocker shafts and the pushrods. Remove the front cover. Remove the camshaft position sensor. Turn the crankshaft to top center compression stroke for the No. 1 piston. Install the timing bolt in the flywheel. Ensure that the timing marks on the following gears are aligned: the camshaft drive gear, the idler gear and the crankshaft gear. Wire the valve lifters away from the camshaft. Remove thrust pin. Install 131-1525 Camshaft Pilot Tooling into camshaft. Carefully remove camshaft from the engine
I think you will have to replace the cam followers that run on the worn cam lobes. If that's the case you will have to pull the head to get the followers out. Oops I forgot you already have the head off again.