340 oil pump gasket?
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340doc
Well-Known Member
A new oil pump should come with a paper thin gasket. Run a fine file over the mating surface on the cap also.
RustyRatRod
Caput villa stultus
I've torn down literally hundreds of engines......maybe into over a thousand. I have seen some that had the gasket originally and some not. I say if you happen to have a gasket. Use it. If not. Don't. As long as both surfaces are flat, IMO, it will not make a huge difference.
I've cut my own out of gasket material when I run out...
Just trace a new or old gasket on the gasket paper and cut it out with an exacto knife....
Just trace a new or old gasket on the gasket paper and cut it out with an exacto knife....
340doc
Well-Known Member
I always feel better with a gasket
TrailBeast
AKA Mopars4us on Youtube
And I never liked the idea of having something compressible between the pump and the block so it could possibly end up loosening up.
RustyRatRod
Caput villa stultus
And THAT is a very legitimate concern, IMO.
Just changed out some oil pumps on 99 5.2...94 5.9...and 88 318...all original engines...no gaskets...melling pumps had gasket in box...did not use them...but I have used them in the past....so...???
I've never had a gasket for an oil pump fail in over 30 years and over 500,000 miles...
If you use a good gasket material that is not very thick, there is very low chance that it will fail...
With a good gasket, it seals completely and no leakage from the pump, better pressure and no air introduced into the oiling system by sucking it up from surface mis match...
If you use a good gasket material that is not very thick, there is very low chance that it will fail...
With a good gasket, it seals completely and no leakage from the pump, better pressure and no air introduced into the oiling system by sucking it up from surface mis match...
I will say as a ex-Mopar master tech the factory didn't use a gasket and in training we were told not to use one. Since the gasket is on the outlet/pressure side of the pump there is no chance of air being sucked in. The stock oil pump is known to be and recommended by many for performance use. I actually use HV/HP pumps in most of the performance engines I build and using a gasket would just cause a possible failure point that is easily avoided. I know using one is considered overkill but many of these engines spin 7000rpm+.
The only oiling system problem I have had was one 4x4 I owned. It cracked a pickup tube in the threaded area by the pump due to an impact on the oil pan. It would suck air and loose some pressure under full throttle but I was still able to drive it home from the trail system without any engine or bearing damage.
340doc
Well-Known Member
340doc
Well-Known Member
That's probably why they make the gasket so thin
nm9stheham
Well-Known Member
I can't get the idea into my head that using a gasket here is overkill...?? Put a sparing amount of #1 or #2 Permatex on it and it will never fail.
At the engine factory that I worked at, we had a problem with the exhaust crossover gasket burning up. We ran a test and left one loose and tightened one properly and ran it on the dyno. The one that was loose burned and degraded to look like cheese cloth and was very brittle with only a 10 hour run, the one that was tightened properly held up fine. We had to error proof the exhaust cross over operation so it wouldn't release the engine until the proper torques were achieved on the bolts, to prevent a loose one from getting out...
If the gasket is properly designed for that application, it will hold up... If you assemble it properly, it won't fail.
TrailBeast
AKA Mopars4us on Youtube
I have seen loose pumps before and chunks out of an old hardened gasket both on the same motor.
Keep in mind that the gasket is only on the pressure side so no air could get into the oil flow anyway, and if there is ANY chance at all that one could come loose or leak any pressure at all why would we do that.
But if one came loose even just enough to let air by, then it will allow the oil in the passages to drain right out after shutdown instead of the pump possibly blocking that backflow. (A small deal, but a deal non the less)
I clean both surfaces and run a tiny bead of RTV around the ports about half way between the ports and edge of the mount flange then put it on and tighten it down.
Done deal, with zero question about staying tight.
I also open the pump and pack the gears with assembly grease just like I do on trans pumps.
It insures a quick prime of the pump on first startup.
I wouldn't be against using a very small amount of anaerobic sealer(not RTV) to insure there wasn't a chance for any backflow but it would take a long time for any significant amount of backflow to occur without anything being used. It wouldn't drain down quickly without a gasket but if a gasket failed it could.
Without a gasket there is only a chance for minimal seepage. Odds are more backflow can and does occur inside the pump itself.
I would be more concerned about any sealer that is used winding up in the oiling system or having a gasket failure then the minimal amount of seepage that could occur if a gasket isn't used.
TrailBeast
AKA Mopars4us on Youtube
Been using the red high temp RTV for this kind of stuff without issue since Kennedy was president.
Most make the mistake of using WAY to much, and on an oil pump surface the amount I use is so small you can hardly see the color of it.
As a hobbyist, I've not done the engine work as some of you, but if I'm using the original pump and there wasn't a gasket, I don't use a gasket.
However, if I'm using an aftermarket oil pump, I do worry a little about the mating surfaces being true with each other and feel a little better with a gasket.
However, if I'm using an aftermarket oil pump, I do worry a little about the mating surfaces being true with each other and feel a little better with a gasket.
TrailBeast
AKA Mopars4us on Youtube
A totally legitimate concern with aftermarket stuff.
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