Low Oil Pressure on Hard Deceleration, 2.056L with Dual Carbs Options

[Spoke]

I bought this allegedly running-when-it-was-pulled 2L engine last year to upgrade to 2.056L just to find out it already had 96mm P&C.

Internals turns smoothly so I thought I'd do the flame test and clean the engine and put it back together. The engine runs strong and smooth.

As I started driving it harder I noticed on fast deceleration the oil light would come on.

If I let the engine speed come down naturally from about 2k, the oil light doesn't come on.

Last night coming off the highway running about 3.2k, I immediately shifted into neutral to let the engine slow on its own, the oil light came on for a few seconds as the engine was now idling.

I don't have an oil pressure gauge on it to see where the oil pressure is during operation.

Any ideas of what to look at?

[Tom_T]

Spoke,

Both my `73 914-2.0 & our `88 VW Westy 2.1L WBX4 (both stock) will do that on occasion under those circumstances of decel. IIRC it's a matter of engine revs dropping fast also drops rpms of the oil pump, while the higher speeds had the oil up into the working parts of the engine, until it catches up & equalizes the OP. If it stays on after the engine settles into idle or the next gear after slowing down, then it would be more of an issue.

It may not be a big issue, although I'll let the actual pro mechanics on here weigh in on that issue.

Meanwhile, you need to change that `Quins logo out for the Steelers one for tonight's opener! (IMG:style_emoticons/default/piratenanner.gif)

PS - You might want to add a VDO OP + OT, CHT & Voltmeter gauges to an auxiliary cluster to keep track of the vitals. If your 71 has a center console (added OE or repro), then you probably already have the OT & VM in it. I'm thinking of getting an old ashtray to mount a VDO 2 gauge mount on the face where the pad is (removing pad) to add the OP & CHT there when I get to that point on mine, but I think a VDO 3x cluster might fit there for your OP too - if not in your center console - or VM there & get a Combo gauge with OT + fuel to swap into the dash pod. I've also seen some nicely done repro center consoles with all those gauges in a modified 5-6 gauge cluster (6 with VDO clock). Also someone on here used to make 4x combo gauges with inserts for fuel + 3, & IIRC North Hollywood Speedo &/or Palo Alto Speedo will do such custom gauges too.

(IMG:style_emoticons/default/beerchug.gif)
Tom
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[VaccaRabite]

Chris Foley was selling a pressure booster that replaced the spring and piston in the relief cavity, IIRC.

I'd put a pressure guage on it to see what your pressure actually is. You should be getting about 10 PSI for every 1000 RPM. The stock idiot light goes off between 2 and 6 PSI, so hopefully the sender on your car is on the higher end of that range.

Zach

[boxsterfan]

Chris Foley was selling a pressure booster that replaced the spring and piston in the relief cavity, IIRC.

I'd put a pressure guage on it to see what your pressure actually is. You should be getting about 10 PSI for every 1000 RPM. The stock idiot light goes off between 2 and 6 PSI, so hopefully the sender on your car is on the higher end of that range.

Zach

(IMG:style_emoticons/default/agree.gif)

That oil pressure relief valve is a problematic design.

[brant]

I'd replace the sending unit too.
put on a dual pole and a real oil pressure gauge
you need to know that info if you want to potentially save a motor

likely you don't have a problem and its a wiring issue
but you need an actual gauge on it, to begin the diagnosis

[TheCabinetmaker]

I don't think Chris' valve was intended to raise pressure, but to increase oil flow to the cooler.

['73-914kid]

I would recommend installing a tuna can on the sump, or slightly over filling the engine. If I remember correctly, (it's been a long time since I've played with stock type 4's) the sump hold's 3.5 quarts. Run it at 4 quarts, which will show a little over full on the dipstick. It's not so full that the oil will come in contact with the rotating crank, but it's enough to prevent oil starvation.

Hopefully someone who deals with these more often can shed some light on the exact numbers, but I'm 90% sure on my memory.

The fast deceleration is causing the oil to slosh away from the pickup tube. I would be very surprised if this is a wiring issue.

['73-914kid]

Also, what oil and weight?

[914Bryan]

I agree with what Ethan said about overfilling the engine about a half a quart. My 2256 was experiencing the same condition, especially on a left turn when the engine was at operating temp. No tuna can installed but by overfilling the sump, there will now only be a momentary flash of low oil pressure, but it quickly recovers.

Hope it helps.

[Dave_Darling]

Every time I have had the oil light come on under hard braking, it's because I've been a quart (or more) low.

Protip: If you count empty oil bottles to remember how much oil you put in the car, make sure to keep your extra empties out of the area...

--DD

[Spoke]

Also, what oil and weight?

Valvoline VR1 20W-50.

When this happens, I thought it may have been from oil sloshing forward but it happens when I exit a highway going from 3K+ to idle and before I start braking.

I do need a gauge. Would this be an oil pump issue or pressure valve?

[VaccaRabite]

Internal clearances may be too high.
But I would check all the other stuff first, and get a pressure gauge on there asap. Until you know what your pressure is dropping to, all we are doing is spit balling.

I don't like the dual pole senders, BTW. They have the idiot light set at about 9 PSI, much higher then the stock sender. I have a single pole pressure sender, and a stock idiot light sender on a Y block.

[Spoke]

I have a single pole pressure sender, and a stock idiot light sender on a Y block.

About the Y block, is this the metal plumbing Y available at hardware stores or special brass Y? Got a pic?

Also, where to buy an oil pressure gauge and sender? I didn't see anything on Pelican.

[Dave_Darling]

Also, where to buy an oil pressure gauge and sender? I didn't see anything on Pelican.

http://www.pelicanparts.com/catalog/SuperC...E_pg2.htm#item7

--DD

[colingreene]

Do you know for sure that the windage tray is in it?

[Spoke]

Do you know for sure that the windage tray is in it?

I was wondering the same thing. Although the last time it happened I was coming off the interstate and shifted into N w/o slowing.