tylergrant2011 Posted March 1, 2015 Share Posted March 1, 2015 Ok so I have an 87 mj 4.0 that has been sitting up for 5 years due to gas milleage. I noticed it was getting no oil after I replaced the valve cover gasket. I changed the oil and filter and still no luck. I took the oil sending unit out and cranked it and no oil coming out of the hole. So I dropped the oil pan. There was a great deal of sludge in the pan. I took the oil pump off cleaned it and the strainer/pickup tube. I put it back on. I put some oil in a container held it over the oil pickup and got someone to crank it and it was not pulling any oil at all. Help would be appreciated. Link to comment Share on other sites More sharing options...
AeroNautical Posted March 1, 2015 Share Posted March 1, 2015 I'd go ahead and stop cranking the engine if it's not lubricating, first off. The oil pump will be the least of your worries if you keep that up. From the sounds of it, yes, it's a bad pump. It's a mechanical pump, geared to the crankshaft I believe. How did the gears look when you took it off? Did you mesh them correctly when re installing it? There is a chance your bearings are bad, too, which would cause low oil pressure. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted March 1, 2015 Share Posted March 1, 2015 Pull the distributor cap and make sure the rotor is turning . The oil pump is driven by the camshaft and the cam is driven by the crank via the timing chain . IMO if you already have the pan dropped and the oil pump accessible I would replace it regardless . I would never let a vehicle sit for 5 years without changing the oil and starting ./ driving it occasionally , even if it's around the block . Many things can go wrong when a vehicle sits for an extended period of time . Link to comment Share on other sites More sharing options...
Jeep Driver Posted March 1, 2015 Share Posted March 1, 2015 All that sludge that was being picked up by the oil pump five years ago has now hardened in the oil passageways/journals. The only way to resolve it now is a rebuild. I'll reserve further comment about those who park vehicles for 5 years. Link to comment Share on other sites More sharing options...
AeroNautical Posted March 1, 2015 Share Posted March 1, 2015 The oil pump is driven by the camshaft and the cam is driven by the crank via the timing chain . Camshaft, that's right. I knew it was one of the spinny rods, haha. Link to comment Share on other sites More sharing options...
shelbyluvv Posted March 1, 2015 Share Posted March 1, 2015 The pump could have lost it's prime. You can also spilt it, pack it with Vaseline and see if it will build pressure that way. The Vaseline will break down in your oil. Link to comment Share on other sites More sharing options...
tylergrant2011 Posted March 1, 2015 Author Share Posted March 1, 2015 I looked inside the oil pump at the gears it was dry as a bone inside so that tells me its not pulling any oil up. Link to comment Share on other sites More sharing options...
shelbyluvv Posted March 1, 2015 Share Posted March 1, 2015 Try the Vaseline and see if it will build pressure. A cheap oil filter will allow the oil to drain into the pan. Once the oil pump loses prime it will very rarely re-prime itself without being packed with Vaseline. Goggle it if you think I'm screwing with you. Link to comment Share on other sites More sharing options...
tylergrant2011 Posted March 2, 2015 Author Share Posted March 2, 2015 Ive packed oil pumps before with a variety of petroleum based products including vaseline. But technically speaking you can prime with just motor oil only. Ive always bought the new pump and put in a pale of oil and spun it with a drill until oil came out then put it in the car and bolted everything back up and added oil and filter. Then spun the pump with drill till oil pressure builds up good enough to safely start. Never had one to have the gears have no wear at all and just not work. I actually think the sludge from the engine made the pump work so hard it quit. Also Jeep Driver has a good point about passageways being clogged. I'm trying to avoid a rebuild. Link to comment Share on other sites More sharing options...
Jeep Driver Posted March 2, 2015 Share Posted March 2, 2015 If it were me.............. I'd take the pump off. Bolt the pan back on with a couple of bolts. Remove the oil sender. Make an adapter to run a line to the sender adapter. Pour one gallon of mineral spirits into a pressure pot...homemade. Use air pressure to force the mineral spirits through the passageways. Use a new oil filter. See if it is clogged, see what come out and collects at the bottom of the cleaned out pan. Link to comment Share on other sites More sharing options...
tylergrant2011 Posted March 2, 2015 Author Share Posted March 2, 2015 I don't have mineral spirits but I do have acetone n paint thinner. Will that do the same? Link to comment Share on other sites More sharing options...
tylergrant2011 Posted March 2, 2015 Author Share Posted March 2, 2015 And when I get it up and running I need some advice on how to increase gas mileage. Ive did basic tuneup on belts hoses fuel and spark. But It still would only get 12-15mpg Link to comment Share on other sites More sharing options...
metrictonner Posted March 3, 2015 Share Posted March 3, 2015 Starter motor cranking is NOT the way to either prime the oil pump or check for oil pressure. Yank the distributor and stick a BIG flat bladed screw driver shank down the distributor hole attached to an electric drill and drill away with the key on. You might get away with desludging your engine innards with kerosene diluted engine oil. Having never tried this myself you might find some recommendations on the internet particularly U-Tube. Link to comment Share on other sites More sharing options...
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