CAT 3412 B Genset fuel injection pump. CAT 3412 B Genset engine serial # 38S8089, Arr.#4N2246 Has anyone ever changed the fuel injection pump plunger assembly top O-ring just below where the fuel injection lines hook up? CAT says you need a 6V7050 compressor group tool to do the job. Could you not just bring each piston 1 at a time up on valve overlap with the injection pump camshaft on the base circle for that pumper unit with minimal spring force pushing up and hold the pump group down with a 8S2244 extractor and slide the bushing up to change the O-ring below. If you did them all in firing order but on the top of the exhaust stroke 1 at a time, could it be done? Has anyone had any experience changing these O-rings that leak from hardening, even though the unit has next to no hours? (1039 hrs) Has block heaters on that made the O-rings hard. Thanks! Simon
I believe you are correct and if you spin the engine over and do them when on TDC you should not need the tool. The last 3406 i did I used the tool but seem to remember a few that landed on the base of the pump cam and had no force on them but be extra careful when you do the first one !!! That does seem strange those orings would leak already. How much heat are the block heaters really getting into the pump ?
The engine sits at 140 Degrees F and has been plugged in like this for 34 Years. Has only 1039 hrs on it. Used 30 hours per year Average. if any one else has experience doing this job on TDC of Exhaust stroke with corresponding PUMP UNIT on the base circle of the pump camshaft please let me know. Thanks for you info ahead. Simon
Yes, in theory you can do what you describe but you have to be super careful about cleanliness. When you loosen the nut it's very hard to avoid generating bits of rust and other crap that will fall down the sides of the pump element. The joint between the pump body and the bonnet is a lapped sealing surface. Get even a speck of dirt in there at your peril. I've done it before with mixed results. So mixed in fact that I now prefer to go the extra mile and remove the pump elements to make sure everything goes back together clean.
Might be easier to take the pump off, and take it to a rebuilder...
Ser.# 38S8089 Arr.#4N2246 Can you tell me if the segment teeth in the Pump and plunger are easy to line up in the bottom of the bore. Can you also tell me the proper tool # to be able to check the fuel rack travel after each unit is changed to be certain of not being one tooth out. I'd like to see a picture of the dial indicator on the end of the fuel rack measuring travel. Thanks Simon
7 To 10 Days return is too long to be without backup power so we will fix in place if possible. Simon
I have done a ton of bonnet seals in 3400s and 3300s and never had a leaker. On most engines I will pressure wash the heck out of the pump cavities. Have a helper to hold the pump down, loosen the nut, turn it back and forth a few times, then blow out the cavity again. remove the nut and using a very small vacuum hose suck everything out of the hole. Cut the old o-ring and carefully roll the new one over the nut with a film of engine oil on the o-ring, reinstall nut and torque to 160 LB FT. With the right help I've done all 6 on a 3306 in 20 minutes on a hot engine.
Thank you for that help, But I have read that the torque for the top bushing is 120 Ft/ Lbs. Can anyone with current SIS Confirm this please. Many Thanks in advance. Simon
hi 150 ft lbs +/- 10 lbs or 205 Nm +/- 14 Nm Mark
Thank you very much Mark250. Simon
The rack is set with a pin and the quadrants on the plungers have a slot in them which engages with a pin down in the hole. If you have the rack in the wrong position, the pump element won't lift out in the first place due to aforementioned pin not lining up. It's not impossible to go wrong, but it's pretty hard.