Bad intake valve?

[KTOWNBOY]

So, I just got an 84 f250 diesel, it starts easy but has a dead cylinder, it seems to be losing compression through the intake on the #5 cylinder, it makes a chugging noise that just gets louder when it revs up. There is also white smoke coming from the exhaust once it has warmed up, the smoke pulses in rythem with the engine.
Could I have a bad seat or burnt valve that is causing this? I was thinking it could also be a stuck lifter since the truck sat quite awhile before I got it.

 

[f-two-fiddy]

It could be a bad valve. Does it make a woofing sound when You remove the air cleaner?

 

[argve]

Welcome to the site!
This has to be one of the best places for information about the IDI's out there and plus there is a good group of people here.

Now for your problem....

I would suggest pulling the valve cover and having a peek, you can even start the engine up with the valve cover off, these things don't fire oil all over the place like most engines - you will be amazed that it even gets enough lube up there to continue to run. and watch for something that looks a miss. Normally on these engines it's an exhaust valve but that's not to say that we don't have problems with the intake valves, that is because of the valve stems have a nasty habit of wearing out, so make sure you check to see that the valve isn't being allowed to tip in it's guide.

 

[Agnem]

X2. Definitely don't run it until you do a visual inspection. These are interference engines and valve problems CAN be fatal.

 

[typ4]

Look for bad springs, if any are burnt black, you have guide problems. Could be a bad rocker or bent pushrod, not likely though, I have never seen a lifter stick on these engines.

All the engines I have seen in the yards around here have had an exhaust valve drop and destroy the engine, about 6 total.

 

[icanfixall]

The early 6.9 rockers were less than stellar. They don't even sell them any longer... The 7.3 rockers work better. This could be a roller lifter problem or as posted a guide problem. Best to pull the valve cover and have a look before you run it much.

 

[hesutton]

I think you should have a good look under the valve covers. Like said above, you don't want this thing to eat a valve. That would be a disaster.

Heath