Low oil pressure under braking and off WOT

[DJCarbine]

I just noticed that my oild pressure spikes down from about 45psi to near 0 when braking at a red light, and it likes to dither down to about 20psi and then back up to normal when I let off the gas at any better than 1/2 of WOT. It is a newer mechanical gauge, and I just wanted to know if this was somewhat normal. When braking, the oil pressure never stays on 0 for more than a second, and slowly rises to 10, 20, then back up to about 35psi.

This is on a stock 66 289.


Thanks!

 

[krash kendall]

If your oil is low it will slosh away from the pick up, resulting in momentary low oil pressure. It may also do this while cornering. Does the low oil pressure light come on as well?

 

[DJCarbine]

If your oil is low it will slosh away from the pick up, resulting in momentary low oil pressure. It may also do this while cornering. Does the low oil pressure light come on as well?

I dont have a low oil pressure light, the stock electrical sending unit/gauge has been disconnected when I installed the new mechanical gauges. I just recently started hawking the gauge, which is how I noticed it

 

[krash kendall]

the stock electrical sending unit/gauge has been disconnected when I installed the new mechanical gauges.

Of course, of course.

So how about your oil level though?

 

[DJCarbine]

Of course, of course.

So how about your oil level though?

Dead on full. First thing I checked....

However, I do recall having carb issues with the primary barrels flooding and causing it to stall immediatly after starting... unless I held me foot in it and kept the R's above 2500. I drove it home 15 miles on the highway like this... thank god for manual transmission. However, my clutch was angry with me, and I beleive maybe gas got in the oil system, thinning out the oil causing this problem?


Does this seem logical?


Or should I just change my oil, and switch to something like 20w50 for maximum pressure....

btw, I drive everyday about 30 miles, better the protection the better... (awkward sentence there )

 

[krash kendall]

20-50 won't give you better protection if if it can't flow through the bearing clearances effectively.

I'm wondering if you may have air in you're mechanical guage line. Do you have the full mechanical type with the rigid oil line running to the guage, or is it semi-mechanical, with wire?

 

[DJCarbine]

It has a cheapo plastic line running from the extention bar in the blobk to the gauge... is there some way to "prime" this line so that the air bubbles wont affect the operation of it?

And how can I check to see that this is the culprit?

 

[krash kendall]

Did an instruction kit come with the guage?

The only reason I mentioned air is because air can be compessed whereas oil cannot. This could explain the rapid drop in pressure on decelleration (as the oil pressure drops with RPM it would allow the air to expand, like releasing the energy of a spring) and the slow buildup of pressure again as the air is recompressed, dampening the effect of the incoming oil against the gauge bladder.

.... or you may just need an oil pan with baffles.

 

[DJCarbine]

Instructions?

They had this peice of folded up paper with ancient Hieroglyphics on it....

Perhaps I will decipher them tonight