Pulling engine and TH350. What to inspect?

[NaturalSnapple]

In about a month or so I plan on pulling the 350 and the TH350 from my 71 C10 to replace seals (both engine and transmission losing fluids). The engine is original but has been worked over by the PO - it has an aftermarket intake, carburetor, long tube headers, and the cam is very lumpy, but I have no details about the cam or even if it's still flat tappet.

With both out of the truck, what would you recommend for me to inspect/replace. Should I pull the heads and check the internals before changing the seals to make sure there isn't anything to be concerned about? I'll be pulling the intake to see what kind of lifters/cam it has, but I'm hesitant about pulling the cam itself.

[custom10nut]

Define "Losing fluid". Have you done a compression test on it? Does it leak oil, or burn it? Have you checked to see that all the bolts are tight? What is leaking on trans? The pan, front seal, or output shaft seal? Does the trans slip? Is the fluid burnt? As with the engine, did you check to see that everything is tight?
You can pull the engine if you want, but checking these things might save you some money and time

[NaturalSnapple]

Originally Posted by custom10nut

Define "Losing fluid"

Dripping underneath the engine and transmission. I can lay under the truck and watch droplets slowly fall from the pans of both. Back of the engine and front of the transmission are covered with oil. Have to add a quart of oil every month. Doesn't seem to be burning.

[custom10nut]

What you're saying sounds like a loose oil pan. Check that first

[NaturalSnapple]

Checked all the bolts on both pans and they are snug. It's looking like the rear main seal from what I can tell. No smoke or odors from the exhaust so I'm pretty sure it isn't burning. No pressure test yet.

The oil is primarily covering the rear and bottom of the engine. None anywhere else. Dipstick tube, valve cover gaskets look good.

The trans shifts great without any slipping, but it definitely feels like it had a valve body upgrade. It shifts very hard and the PO installed a B&M ratchet shifter to go with it. The leaking from the transmission seems like it's from the pan so that seal is probably trash. If I'm pulling the engine to redo the RMS I think it would be easier to pull the engine/trans together instead of trying to support it underneath, and I can just redo the seals with it pulled.

[CharlesUFarley]

You should do a compression test and a leak-down test to see if its worth putting back in. The compression test is done by connecting a compression tester to each spark plug hole with all the plugs removed from the engine and the coil wire disconnected. Crank the engine so it cycles 5 or 6 times and then record the PSI on the tester. The compression test should result in all cylinders making roughly the same amount of pressure (within 10% or so).

The leak down test consists of connecting compressed air to each cylinder at top dead center (of each cylinder). This will tell you if and where its losing compression. If you hear the air blowing from the carburetor, compression is leaking past an intake valve. If air is blowing from the exhaust pipe, you have an exhaust valve problem. If you can hear air coming from the oil filler cap, that would be bad rings. This is all probably a slight over-simplification, but a good place to start.

[NaturalSnapple]

Originally Posted by CharlesUFarley

You should do a compression test and a leak-down test to see if its worth putting back in. The compression test is done by connecting a compression tester to each spark plug hole with all the plugs removed from the engine and the coil wire disconnected. Crank the engine so it cycles 5 or 6 times and then record the PSI on the tester. The compression test should result in all cylinders making roughly the same amount of pressure (within 10% or so).

The leak down test consists of connecting compressed air to each cylinder at top dead center (of each cylinder). This will tell you if and where its losing compression. If you hear the air blowing from the carburetor, compression is leaking past an intake valve. If air is blowing from the exhaust pipe, you have an exhaust valve problem. If you can hear air coming from the oil filler cap, that would be bad rings. This is all probably a slight over-simplification, but a good place to start.

Thank you! I'll definitely do that before I pull it out of the truck.

[custom10nut]

Pull your plugs to see off its burning oil. More more it sounds like you just need new gaskets.

[NaturalSnapple]

Thanks everyone, I had a chance to pull the plugs and compression check the engine today. Looks great as far as I could tell, except for a burnt wire due to proximity to a header tube. No oil on the electrodes or any physical damage. Went ahead and changed the plugs and wires just because I had it all torn out. Also installed new valve cover gaskets since they were leaking just a bit.

For compression check I did it with all the plugs pulled out, coil wire removed, and let the starter pulse 5 times for each cylinder checked. Warmed the engine up for about 5 minutes prior to pulling the plugs.

1 - 159 psi
2 - 148 psi
3 - 150 psi
4 - 150 psi
5 - 148 psi
6 - 150 psi
7 - 150 psi
8 - 149 psi