The GMC CCKW

Hello All,Following the need to shut down a seemingly normaly running engine because of a water pump leak,the pump was removed and had new seals etc fitted.I refitted the pump a few days ago (new gasket) started her up almost first turn and had to switch off within 15 secs as the oil pressure just did come up at all did all the usual checks oil level fine check oil pump strainer in oilpan,drained oil checked strainer bit of sludge no debris,checked the old oil no debris or metal bits new oil start up still ZERO OFF ROCKER COVER start up 15 secs no oil up to rockers shut down, no oil to gauge ,no oil to filter PANIC What the heck is wrong have I made a mistake refitting the water pump? could any of the three bolts that hold on the pump be blocking an oil gallery,have I missed cutting a hole/holes in the water pump gasket? is the small three way block down by the generator blocked? will that small 3 way block screw out from the engine block? or can it only be the oilpump??HELPFUL IDEAS PLEASE or a box of matches

One thing you can do instead of running the engine is to remove the dist and insert a flat-bladed (wood) drill bit into the dist hole on the end of a drill. Make the drill bit a little smaller than the dist screwdriver blade on the end of the shaft. Make sure you turn it in the right direction too.

You can run up the pressure into the engine by doing this. You will also be amazed at how much energy it takes to run the pump!

Thank you 4 that Dr,But does any one else think it could be ANY defect,other than the pump Can you change the pump thru the sump? is it a BIG job ,Is a total failure of the pump common? I just cannot get my head around the fact that the pump seems to have failed whilst standing just four months, to get ZERO pressure the pump drive will need to have failed/broken? would I expect some awful noises if it had? or the pump suction pipe?How can I test to see if the pump is putting ANY fluid out?I am just looking for a way to eliminate ALL other possibilities, BEFORE ripping out the bottom end to change a pump that may not have failed.TO RE-ASK does any one know if the small 3 wayblock that takes oil lines to the filter,gauge,cyl head situated down by the generator SCREWS out of the engine block I would like to check that it is clear and if I use the good Drs method to spin the pump I could monitor any output at that point if the block was pre proven clear of obstruction I await the avalance of replies PLEASE

I believe there is a pressure relief valve in the system. Maybe that is stuck open (in the relief position).

If you dont want to immediately drop the pan....which I would do regardless.

I would drop the oil and try and push some Kerosene through the pump to see if that will free-up a stuck valve.

Can't hurt. Kero will help pull some sludge out.

But I would drop the pan. You don't need any surprises on the road.

Bill

Could also be something (crack etc) wrong with the pickup tube.

As suggested have removed dizzie and run up the pump with a drill,still zero flow or pressure,however did you say that it would take a fair ammount of energy to spin the pump If so there may be a break in the drive to the pump gears somwhere as I can spin the top of the pump drive with ease!by hand just using a very long srewdriver.any other tips I plan to drop the oil,mesh filter, deep sump and pick up, soon and check the pipework,then the large sump pan to access the pump itself, will keep all interested parties up to date on what is found,thank you all for the advice

You can turn the pump with a screwdriver by hand. If it turns easily with a drill, I suspect something inside the pump or more likely something in the pickup tube.

Also, do you have 10 qts of oil in it? Assuming the std CCKW oil pan

Remember, you HAVE to take the lower pan off 1st to disconnect the pick up line.

8 QUARTS PUTS THE OIL LEVEL ON FULL (WITH THE FILTER M/T)TOPPED UP TO 10,REMOVED PLUGS.TURNED OVER WELL ON THE STARTER STILL NOT A DROP!! SO HAVE DRAINED OIL, WILL DROP LOWER SUMP AND REMOVE PICK UP ASSEMBLY. CHECK THAT OUT AND REPORT BACK STAY TUNED!! THANKS AGAIN TO ALL BUT JUST TO CONFIRM TURNING OVER THE PUMP( WITH THE DIZZIE REMOVED) AND USING A LONG SCREW DRIVER COULD BE ACHIVED REAL EASY WIYH JUST THUMB AND FORE FINGER NO REAL RESISTANCE AT ALL AND IT JUST FELT A LITTLE "GRITTY" AND "ROUGH"NOT AS SMOOTH AS I WOULD HAVE THOUGHT COMMENTS PLEASE

I see a new oil pump in your future

Thanks for keeping us posted.

Cheers
John

And the winner of The guess whats wrong from 4000 miles away competition is . ...ADMIN .. Well done BILL.. your prize as soon as I can get the cork back in the bottle will be on the way to you shortly.>> After dropping the sump etc to get the pump out ,stripped the pump and it was a surprizingly small piece of crud in the bore wall of the pressure relief valve..keeping the valve in the fully compressed postion i.e"closed" so the pump works ,pumps the oil but the lube oil just recircs cleaned it all ,polished the shuttle vaive body and the bore replaced the spring will a bit harder one to stop the vave being pushed to the extreme end of its travel. bench tested the pump ,all seems well pumps just fine , will reinstall it all next weekend hopfully and run the engine again will keep you all posted, Thanks for all the help guys ... I expect I will be back soon with the "next problem" Thanks again