Broken IDI!!

[Sealboy_04]

I just got my baby back from compression test. I have 350-400 psi on cylinders 2-8. 50 on 1!!!

I don't know what to do! Mechanic didn't have leaks own and thinks the leak plus in the exhaust valve. But doesn't know. Trucks got 307000 miles but runs smooth until it shifts into od. Any help would be appreciated

 

[icanfixall]

Might be a bad valve guide or a bent pushrod tube too. Sorry to say this but its time to remove the worst valve cover and have a look see.

 

[Sealboy_04]

Would it be worth it to have the head rebuilt? And how can I tell if its a valve or rings or cylinder cavitation?

 

[Hydro-idi]

Does the exhaust have a whooshing sound to it at idle? Rough idle? If so, this could be a bad exhaust valve. If not, there's other issues. A bad injector could have washed down the cylinder which would require major attention if you wanted to get it fixed. It could also be stuck piston rings, but I would lean more toward a washed cylinder.
FYI a washed down cylinder means an injector was spraying too much poorly atomized fuel, taking the oil lubricant off the cylinder walls and eventually frying the rings....too much friction.
How's engine blowby??

 

[Sealboy_04]

The only rough idle is cold. Then it just shakes a bit but jot too bad. No popping at idle. And please explain blowby if you could.

 

[Hydro-idi]

Blow-by is a result of piston rings that are not sealing properly. Naturally, these idi's tend to have some blow-by due to the rings that international used in these engines. With the engine running, pull off the air intake and you will see CDR feeding blow-by back into the engine. Also take off the oil fill cap with the engine running and let us know how much blow-by you see. My guess is that you will see quite a bit if one cylinder tested @ 50 psi, and if the cylinder is in fact washed.

 

[Sealboy_04]

What is the cdr? And where do I look to see the oil?

 

[Hydro-idi]

The CDR (crankcase depression regulator) is mounted directly behind the intake manifold. It looks like a tuna can. It redirects blow-by back into the engine and is similar to a pcv valve for a gasser. But if you have the air intake bowl off, you will be able to see blow-by being sucked back into the engine (might need a flashlight if doing it now). Also remove oil filler cap to see if blow-by is huffing from the filler neck. This means that the CDR is unable to keep up with all of the blow-by that your engine may be producing. Have engine running when doing this.

 

[Sealboy_04]

Ok. Thanks for the info. I can still plow with t but I know it's not good on her. But it's lookin like a rebuild for me or a used engine. Nobody knows of someone having a used IDI in the Indiana area huh?

 

[Hydro-idi]

I could be wrong with your engine having a washed down cylinder. Don't get to hasty now lol. These are just my thoughts but it could also be a bad valve. Do further testing on your engine before kicking around the idea of putting a different engine in it.

 

[Wyreth]

You do not need a leakdown test kit, just have him do my "poor mans leakdown test" First get an airgun that has a rubber nozzle. (Harbor Freight for like 5$) Then pull the glowplug, for that cylinder, and put the nozzle of the airgun in it. Make sure the piston is on the compression stroke so both valves are closed, also turn down your pressure to about 20psi, then blow. If you hear air hissing out of the intake, or exhost. You have a valve problem. If you get air out the dipstick tube, you have a ring/piston problem. If you get bubbles in the radiator (you should take the cap off when you do this) then you have HG issues, or cavitation.

If he thinks it's a bad valve, then that will tell him. Altho, with compression that low, and oil not bubbling out the dipstick, I am also inclined to believe you have a valve issue.

Short answer, I personally believe it would be worth a head rebuild. Depending on what you'd be paying for it. (shop around)

 

[Hydro-idi]

^^^I was just about to suggest an idea similar to Wyreth's. It is easier to pinpoint problem when the right testing is performed.

 

[diezelcrazee]

I once had a 90 Dually IDI and it got to missing at idle and you could hear it in the exhaust. It turned out to be a (actually several) bad valve guides. I wouldn't write your engine off yet, do the simple cylinder leak test that Wyreth outlined and see what you find.

 

[Hydro-idi]

I once had a 90 Dually IDI and it got to missing at idle and you could hear it in the exhaust. It turned out to be a (actually several) bad valve guides. I wouldn't write your engine off yet, do the simple cylinder leak test that Wyreth outlined and see what you find.

Did it make a whooshing sound from exhaust or just a miss sound? Just curious like always lol.

 

[riotwarrior]

Seaboy 04 perhaps read the FAQ's and such to give yourself a much better understanding of these engines....There is some great basic info in there to help you out and help you make educated and informed decisions and questions.

Even a bent pushrod or cracked/broken rocker arm could cause this too.

Pull the valve cover of the side with the low compression, disconnect the FSS and then turn engine over a few times. see if the valves are all opening the same amount and if it all looks good.

If it's all good, then perhaps it is time to have it looked at in regards to pulling head and having it redone, and since your in for a pound....do both! it's just one more gasket and a little more work...