i have a 1990 f250 7.3 idi non turbo. I just got done re doing the head gaskets on it everything has been going great for a couple days. But I notice it has a knock when first start til oil pressure comes up on the gauge. It never knocked before is the oil going bad? It still has four injectors that need replaced. If you start it up it will knock til the oil pressure it up then if you turn it off and back on it won't knock. I'm confused on what to look at.
7.3 idi knock
- Thread starter Fordfan90
- Start date
icanfixall
Official GMM hand model
This sounds like a mechanical issue but I sure would replace those bad injectors ffirst. Many times I have seen or heard bad injectors causing a rod knock sound. Whats happening is the injector spring weakens over time so they open early cauing a fuel knock. It really does sound like a rod or main bearing knock.. Its really an easy repair compared to replacing bearings or crank.
Do you think maybe the oil pump is going bad?
Hydro-idi
Full Access Member
These oil pumps rarely go out if at all. Likely not the problem.
icanfixall
Official GMM hand model
not at all likely the oil pump failed. These are very well built oem oil pumps. you said it yourself.. Some injectors are old and you need to replace them but.. you want to go in deep... then pull the engine and take it ALL apart. The nearly free advice given here is from many years and thousands of questions asking the same thing. Nobody here can MAKE you replace anything but we sure can give well known sound advice as to what we read or listen to. Remember this. You pulled the heads and any dirt you did not witness on top of any injector has compromised said injector. Before I open any injector line I clean off the area with plenty of brakclean. I wear plastic work gloves and when they look dirty I change them. Cleanliness is your friend. Never think you have "things" too clean either.
Thanks you I'll look at getting some injectors for it. Maybe some dirt got In them. The knock only happen when you first start it and it didn't have a knock for a couple days til now. The engine shake a lot and the dual mass fly wheel is rattling like crazy. If I have to I'll rip apart the whole motor and do a rebuild
JAKRANCH
Full Access Member
Did you get to the bottom of your knock? I have a similar issue after redoing return lines.
pelky350
Full Access Member
If the the motor is shaking during the knocking and as mentioned the injectors are old if one has failed and it's misfiring it can sound like a Rod knock
JAKRANCH
Full Access Member
They seem newer they're bb codes on a 6.9. Didn't the 6.9's have different stock injectors?
jwalterus
Made in America
The chances of it ACTUALLY EVER being your oil pump are next to nil.
Those of us on the forum who have had one fail in an engine that is otherwise sound is a fairly exclusive club
Change the oil filter, and while it's off, check the bypass valve if you are worried about your oil system.
Those of us on the forum who have had one fail in an engine that is otherwise sound is a fairly exclusive club
Change the oil filter, and while it's off, check the bypass valve if you are worried about your oil system.
Macrobb
Full Access Member
Honestly, I really recommend buying a cheap injector pressure tester. These injectors are easy to test, and it isn't hard to find one with a problem, if it exists.
You can also see the pressure variation, and can re-shim them if needed(though this is hard, as you have to have enough salvaged shims to do the job).
You can also see the pressure variation, and can re-shim them if needed(though this is hard, as you have to have enough salvaged shims to do the job).
Will do I notice if you move the pump toward the advance side the knock gets louder but as you give it throttle it goes away. If you move it more retard the motor get quite and the knock goes away. I checked the oil in it today and it's got little metal specs in it?
Macrobb
Full Access Member
Yeah... get some good injectors first off.
Then, next problem.
