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jagman

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My 720 is all together and is starting and running well.  I have put about 100 miles on it since I replaced the head gasket, clutch assy and rear seal.  There are no oil leaks and the smoking problem has decreased  and only occurs when I decelerate on long downhills.  It is still burning oil Just at a  much lesser rate.  There is an oil indicator on the console and a red light on the dash.  The console indicator will give a reading when  I first startup then recedes to zero pressure but the red light on the dash never comes on.  What is the problem?  and how do I fix it?  Thanks Steve

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The red light on the dash should come on when the ignition is turned on to show that the bulb is not burned out. It should shut off and stay off as long as the oil pressure is above about 8 PSI.

 

By 'oil indicator' I can only assume you mean the oil pressure gauge?

 

The 720 4x4 uses a single sensor for the gauge and the red low pressure light. Make sure it is plugged in securely. If this does not resolve the problem replace the sender, about $20 at NAPA or where ever. Use a spanner to remove and install the new one. NEVER twist the case by hand, trust me other than to start the threads.

 

 

The smoking can only be worn rings or worn valve guides so nothing that can easily be done there. However, you can replace the valve guide seals which may be old and not controlling the oil getting down the valve stems. There is a very easy way to do this without removing the head and not using any tools. The seals are less than $2 each. Not a big loss if this does not fix the problem. 

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Mike,  I have been to my erstwhile auto parts guys and they don't have a sender for me that looks like the one I have and you show.  Who has this item and what is the part number if you have it.  This truck is not a 4x4 just a 2x2 . Bonker Beggar here again.  Steve

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Mike mentioned a way to replace the valve seals without removing the head.  I would like to attempt this. I have new valve seals an air hold chuck and overhead valve spring compressor.  Do I have to remove the cam shaft to do this?  The last time I did this I lost the timing chain (bitch) so if I have to remove it I am going to wire the chain to something solid cause the wedge slipped. And Mike thanks for the VIN info the junker is about 8000 units newer than the one I have and has all the parts that are either missing or broken on my "driver"

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Get some nice flexible soft rope that will fit into the spark plug hole, with the piston part way down slip some of the rope into the spark plug hole, enough to cover the top of the piston, then turn the crank by hand(all spark plugs removed) till the rope jams up against the valves, put it in gear with the e-brake on and you can now replace your valve seals on that cylinder.

The rope needs to be a soft flexible type that conforms to the head shape once pushed against the head/valves.

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I do not know about Z24 heads other than they have the valves angled towards each other with a good sized pocket between the piston top and the valves, so you need lots of rope in the cylinder to fill that pocket to hold the valves against there seats.

You may even need to put the rope in the cylinder on the compression stroke so the valves are both closed while the piston rises.

I have heard of others that use air to hold the valves in position, I am sure there are several ways to do it, I just think the rope method is likely the safest and you do not need an air compressor.

I have no idea if the seals can be changed without removing the rocker assemblies, but the rocker arms are going to need to be out of the way to work on removing the valve springs, it appears that there are springs holding the rockers in position, maybe if you loosen the rocker arm adjustment you can push them too the side to get to the tops of the valves.

 

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Take the valve cover off and turn the engine till both intake and exhaust valves are closed on #1. This confirms the compression stroke. Back the engine up 1/4 turn and insert your rope as wayno suggested. I tie a big knot on one end so there's no way to have it fall in. Turn the engine back towards TDC by hand with a 27mm wrench or socket till tight. The valves are no forced against their seats and you can compress the spring, remove the keepers and slip the seal off. Back the engine up enough to free the rope and put into cylinder #3. Turn engine ahead till it compresses the rope tightly and do both valve seals. Next is cylinder #4 and last is cylinder #2

 

Yes the two rocker shaft assembly will need to be removed to get at the springs. Loosen all the bolts, 5 per shaft, in several stages, not all at once. For heaven sake do not over tighten the bolts that hold the rocker shafts when putting them back together. Aluminum is soft and will strip. 11 - 18 ft lbs so try for 14 or 15. Snug then in stages working from the center out to each end to compress any valves that are open.

 

Grease the seals before stretching them over the valve ends and push all the way down.

 

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