IP priming questions

[79jasper]

I wouldn't quite follow what it says, just crank up the pressure and let it go.
Then start finding where it's coming from.

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[homelessduck]

After messing with it for awhile I realized that it is just a junk tester. I'm going to return it and make one.

However , I am having trouble finding tdc for each cylinder. How exactly are you suppose to do it on these engines ? I can verify that both valves are closed but I have no idea how to tell if it is tdc.

Also , the compression tester adapter hooks straight to an air hose so I dont actually need a leak down tester to just listen for air leaks lol. Or am I missing something.

 

[79jasper]

Yes, only need air. Lol
" Pull the valve cover. When the valves are both closed(rockers are both lose) on #1 you are at TDC #1. If the exhaust valve is just closing and the intake is just opening you are 180* off, turn it over one revolution to bring it to TDC compression.
This gets you closest. Watch intake valve close while rotating engine and once both are closed, when the cylinder is at max travel that is TDC. You can get it pretty close without having to pull the cylinder head."
Can even go in the firing order, so you won't have to keep spinning the engine as much. (Which wouldn't be hard anyways, with all the GP's pulled)

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[homelessduck]

Why does it have to be at tdc ? Wouldnt it work just the same no matter where the piston is in the stroke as long as both valves are closed?

 

[79jasper]

Yeah, but also, can't have the piston midway. It'll spin it.
I don't know the reasoning for tdc, I would think bdc would be better.

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[homelessduck]

Alright , sooo... Both low cylinders are leaking out of their intakes.. and a few cylinders had a slight leak on their exhaust. Sounds like the valves are toast ..? Earlier in the thread I said I checked the oil and it was gone. I had checked it long enough after cranking , or so I thought. I just checked it again and it is showing oil.. im not sure why it took so long for it to drain back in to the pan after cranking.

 

[79jasper]

Someone had said a certain year range was common to Crack at the valves.
Can't remember the years, nor who said it.

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[4x4manonbroke]

Oil drains slowly from the heads and turbo on these engines ... ( Same with the Detroit 2 storkes i build ) ...

It does sound like you have a cylinder head/valve issue .. hope it just the seats and not another famous cracked head .... thats what happened to the 6.9 that was in my truck from factory ( now a 7.3 IDI truck) ..

Where in Oregon are ya ? I'm not too far away ..

 

[79jasper]

I'd go ahead and pull em now.
Getcha some wd-40 or the like, and spray it in the exhaust port, see if it leaks.
Then clean it and do the same on the intake ports.
Or just take it to a shop.

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[homelessduck]

I'm in Ruch , small town outside of Medford / Jacksonville. So is there anything else I should do before pulling the heads ? Im anxious to see what it looks like

 

[homelessduck]

You posted that while I was posting my reply ( I get side tracked easily ) haha.

I'll pull them tonight then !

Thanks guys !

 

[79jasper]

Not a whole lot else you can do with them on.

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[Black dawg]

If the heads are coming off anyway, just pull the rocker shafts, and then air up the cylinders. Just watch out for engine (fan and belts) turning over. Also pull the coolant crossover, have coolant filled just to the opening in the head, and pressurize each cylinder for several minutes. You will see bubbles in the port on the head, indicating which cylinders the gasket has failed on. The gasket doesnt always look failed, and can be very tough to figure where the problem was without doing this test.

Also with the cylinder pressured up, if a valve is leaking, tap on it with a hammer, to make sure a piece of carbon (or something) isnt holding it off of the seat.

 

[homelessduck]

I tried that , didn't see any bubbles in coolant. I didn't try smacking the valve but I will do it on the other head before I pull it. The passenger head is unbolted and waiting to be lifted out. I cant get to the rear most head bolt on the driver side , I'm not sure what to do about that ... a minute with a cut off wheel would give me plenty of room but I hate to cut it up

 

[Black dawg]

you will be surprized how strong that part that you need to cut up is