Slant Six Forum
https://slantsix.org/forum/

Anti-Drain Back Valve
https://slantsix.org/forum/viewtopic.php?t=38479		 Page 1 of 2
Author:  DonPal [ Fri Jan 01, 2010 1:54 pm ]
Post subject:  Anti-Drain Back Valve
My daughter's 65 Dart takes considerably longer to get oil pressure up from a cold start than my 65 Dart. I've tried her car twice in the same day with cold starts & got the same result. Her car has a bottom end knock while the oil pressure comes up for at least 10 seconds. My Dart is quiet from the instant it starts.

Both Darts have new oil pumps & identical oil filters (NAPA 1806 that have been changed multiple times. Both have less than 60k miles & both had rod bearings replaced 2k miles ago & were within specs on clearances & roundness. Both use the same oil...Mobil1 10W30. Both Darts have new oil pressure switches.

One difference between the two cars is that her's has a 70's head with peanut plugs while my Dart has the original drool tube. Otherwise we are setting both cars up identically (HEI, heated air intake..etc).

One Slant sixer indicated an Anti-Drain Back Valve is available "(anti drain back valve (in the stand pipe) mopar still sells them 3577848 lists for $35.75)"

Does the 65 Dart have this type valve & could it be defective in her car?
Author:  hantayo13 [ Fri Jan 01, 2010 2:23 pm ]
Post subject: 
is there a stand pipe on pump????
Author:  Aggressive Ted [ Fri Jan 01, 2010 2:33 pm ]
Post subject: 
Good question....if not the tall standpipe is it the short standpipe with no drain back valve?

The 1806 should be holding enough oil to eliminate the problem.

Was the pick up screen clean on your daughters car? Is it getting good flow?
Author:  DonPal [ Fri Jan 01, 2010 2:46 pm ]
Post subject: 
Pickup screen & oil pan were cleaned when the rod bearings & rings were changed.

I won't see the car for 3 weeks so I will get the standpipe configuration at that timeframe.

Based on your response is it true that some engines have a short standpipe with no anti drain back valve and others have a long standpipe with anti drain back valve? Is the long standpipe with antidrainback valve redundant with oil filters that have a drainback valve? Two drainback valves are better than one?
Author:  Aggressive Ted [ Fri Jan 01, 2010 4:47 pm ]
Post subject: 
Quote:
Based on your response is it true that some engines have a short standpipe with no anti drain back valve and others have a long standpipe with anti drain back valve? Is the long standpipe with antidrainback valve redundant with oil filters that have a drainback valve? Two drainback valves are better than one?
Most new pumps may not have any standpipe or they may come with the short one. In both cases I have seen them without drain back valves.

I kept my old standpipe and installed it on the new pump. I removed the drain back valve when I made the switch. Using the WIX 1806 standpipe type oil filter I have not experienced the start up knock. However, it wouldn't hurt to have both........then you could rule them out.

I wonder if you just might have a bad pump or an air leak from a crack in the pick up tube.
Author:  DonPal [ Fri Jan 01, 2010 6:48 pm ]
Post subject: 
Then this doesn't sound like a drainback issue.

We'll add an oil pressure guage by teeing into the oil pressure switch location and get some readings at that location to see if the pump is operating at a reduced capacity(in about 3 weeks).

I'd expect 40 to 60 psi at 1000 rpm based on the 65 FSM specs.
Author:  SlantSixDan [ Fri Jan 01, 2010 8:50 pm ]
Post subject: 
With an 1806 filter, you do not need to be worrying about the antidrainback valve/standpipe. The internal standpipe in the 1806 filter does the same job as the screw-in standpipe/valve, and does it with less flow restriction.

Even with a new oil pump, it's a good idea to make sure the oil pressure relief valve is working correctly, as described in these two threads: thread 1, thread 2.

The question about the condition (cleanliness) of the oil pickup screen is a good one, though if you were in there to put bearings in just 2k miles ago, that's probably not it. How cold are we talking about when you say "cold starts"? 10w30 may be inappropriately thick for the ambient temperatures; I'm running 0w30 (zero-w-thirty) synthetic in my '73, and the oil light goes off immediately with no rod thunk even on super-cold startup (now that I've replaced the fuel pump that was contaminating the crankcase oil with gasoline).

Another question: Where is the oil pressure sender on these '65s? Is it screwed into the oil pump, or into the side of the block itself near the rear?
Author:  madmax/6 [ Fri Jan 01, 2010 9:20 pm ]
Post subject: 
Dan,Question on your question.Will oil pressure read differently from the two different spots?Curious.Mark
Author:  SlantSixDan [ Sat Jan 02, 2010 5:03 am ]
Post subject: 
Yup. There's a TSB published in (IIRC) mid '65 saying slow oil light turn-off on models with the sender in the block can be cured by moving the sender to the oil pump. The block location was used only briefly, I think late '63 to early '65.
Author:  DonPal [ Sat Jan 02, 2010 7:27 am ]
Post subject: 
Quote:
How cold are we talking about when you say "cold starts"?
Another question: Where is the oil pressure sender on these '65s? Is it screwed into the oil pump, or into the side of the block itself near the rear
Cold ambients generally run high 20's to low 30's F in the winter.
The oil pressure switches are screwed into the oil pumps for both Darts. Rod clearances ran .001 for both Darts.

The beauty of two identical Darts: theory of relativity applies & helps reduce the human judgement factor. When there is a distinct performance difference then it points to something that isn't identical. I'm comparing both cars at the same ambient with the same oil & filter so it might be some of the things raised outside that loop. Changing the oil for both Darts to a lower viscosity sounds like a good idea for the winter.

The pump/pressure relief will be compared by measuring oil pressures & timing how fast each get up to pressure. I'll use the same guage & hookup for each. I'll retry her Dart's pressure after pulling the pressure relief & inspecting/correcting.

Since it has been pointed out so many times before here....new parts don't guarantee new "quality" part performance......verify.

ps: Ted's point about a crack in the pickup tube has me worrying. The tube is long, has lots of leaverage, and has threads cut at the connection(the point of highest moment/load). A crack at the thread/block connection wouldn't be good?
Author:  madmax/6 [ Sat Jan 02, 2010 7:59 am ]
Post subject: 
Thanks Dan,I knew you would know.Mark
Author:  SlantSixDan [ Sat Jan 02, 2010 8:12 am ]
Post subject: 
Quote:
Cold ambients generally run high 20's to low 30's F in the winter.
With nice fresh bearings such as you describe, 10w30—even synthetic—is on the too-thick side of things for fast oil pressure on cold start. Try a switch to 0W30 (I use Castrol Syntec) and see how that does. I found a noticeable improvement in oil pressure speed on startup even switching from 5w30 synthetic to 0w30 synthetic. Don't be afraid of oils that would have been considered unreasonably thin in the past!
Quote:
Ted's point about a crack in the pickup tube has me worrying. The tube is long, has lots of leaverage, and has threads cut at the connection(the point of highest moment/load). A crack at the thread/block connection wouldn't be good?
Ted's right that an air leak in the pickup assembly could cause slow startup pressure. Fortunately, though, cracks in the pickup assembly are very rare, and cracks in the block at the pickup thread are virtually unheard-of. The odds of finding one cracked pickup are scant enough; the odds of finding two (one on each of your cars) are beyond remote. Move this down on the list of possible causes.
Author:  olafla [ Sat Jan 02, 2010 9:00 am ]
Post subject:  Anti-Drain Back Valve
Hi DonPal. Since your cars are identical, may I suggest that you exchange parts one by one until you see the problem appear on your car? It's a dirty job in the cold, but if you could switch oil pumps between the cars and see if the problem still is there?
Happy new year. Olaf
Author:  sandy in BC [ Sat Jan 02, 2010 12:17 pm ]
Post subject: 
Have you thought about piston slap?

Is this rod bearing related?

Can it last 6 weeks?
Author:  DonPal [ Sat Jan 02, 2010 12:33 pm ]
Post subject: 
Your right about swapping parts by considering the cold....my garage doesn't get up above ambient outside temps.

65 Dart oil pump changing extra steps include draining the coolant, removing the radiator hoses, disconnecting the motor mount/hoisting, blocking the right side & sliding the engine with a crow bar 1 to 2 inches to the left. With my hoist I have to remove the hood also. A job when temps are decent

I think I'll first measure pressures & time to full pressure for both Darts. Then check the oil pressure relief valve & lower oil viscosity on her Dart before remeasuring.

Oil pump change will come if I can't get decent pump performance.

Bores were checked when the rings were replaced and had only a .001 taper. Ring gaps with the new rings were a tight .015. Piston skirt clearance ran .001 to .002. Knock disappears when the oil pressure light goes out. Consequently I'm assuming piston slap is not the issue.

Can it last 6 weeks? I'm hoping with a knock that lasts 10 seconds only in the winter months will be cured enough with reduced oil viscosity & oil pump attention to be off the "HOT" list.
Page 1 of 2 All times are UTC-08:00
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/