cainmin

Just did an Overhaul on my 1998 4.2. Pulled the motor, new bearings (Main and connecting rods), lifters, gaskets, Planed the heads, 1 new piston(and connecting rod) and rings, Timing chain, sprockets, tensioner, water pump, cleaned Oil pump, Pick up tube was also cleaned of debris, push rods were cleaned no warpage, a very thurough job if i do say so myself.

Here's the problem: I turned it over for the first time, and I'm getting no oil pressure,(Idiot light). I just bought a new oil sending unit and I will put that in this weekend when I go to my shop. I also found the dip stick tube was broken, I bought a replacement for that.(Not sure if that could cause low pressure or not.) I'm thinking that the oil pump check valve may be dirty and stuck? I didn't mess with it at all when I cleaned it. I'm looking for a number of suggestions before I head up this weekend.

Thanks!

akdoggie

Think this way. What causes oil pressure? The pump is number one. I'd check there before going on. You didn't replace the cam bearings did you? If you did, it could be there, if you didn't, then I'd certainly check the oil pump first. Why didn't you replace it when you bought all the other new parts? Did you plastigauge the bearings when reinstalling new ones? If there was significant clearance, it could lower your pressure, but not stop it all the way. Did you reinstall the oil pump shaft? It sounds like it is pump/shaft related, IMO.

gfh77665

No offense, but did you refill the oil?

kd4gij

A new oil pump is on the top of the list when rebuilding a motor. Did you prime the pump?

cainmin

I put oil in the filter I did not prime the pump. Also, I didn't see any reason to replace the pump, checked with feeler gauges, and there was no warpage. However, Air in the pump could cause problems if its just sucking air.

Does anyone have any recommendations on how to do it with this specific pump? I filled the filter before installing it already.

cainmin

The oil pump shaft is attached to the timing cover, I didn't take it off, just cleaned vigorously around it. I didn't touch the camshaft at all, (Probably the only thing I Didn't pull) Mic'ed the lobes, no flat spots, and all was good, so i left it alone. I Mic'd the bearings that i didn't replace, All still on size (Good sign). I'm gonna do some research on priming this specific pump, do that and if its still not working Ill replace the pump. Any suggestions or recommended videos on how do do it properly?

akdoggie

Pack the gears (2) with vaseline. Works everytime, and when you change the oil in 500 miles, you won't find any globs or such. It all spreads out. Its 100% petroleum based so it will not hurt your engine. Best and cheapest and easiest way I know how. I'm sure there are other ways, but to be 100% sure with this kind of pump, you have to pack it and make it accept oil. It's not like a sump type. It is a basically remote pump..

papa tiger

Pump or connection

cainmin

I'm gonna give that a try. I was just talkin with a guy i work with, I guess i forgot to mention i only ran the motor for about 5-10 seconds before I realized that the gauge said there was no pressure and the oil light came on. I shut the truck off immediatley. Should I have waited a little longer for pressure to build up? I'm just nervous about the bearings and the crank

Carcrazygts2

Should have replaced the pump. 97/98 were notorious for pump failures around 125-130k miles.