Mid range marbles and oil pressure question

MizPahPAH · Post by **MizPahPAH** » Sat May 30, 2009 9:27 am

I started in on the Fuel system on my "new" to me 86 jetta 1.6 NA.

Replaced the injectors
installed clear fuel line just before the filter.
Checked the Timing it was set at 1.05mm
Checked the fuel pressure it was at 12psi at 950 rpm.

I reset the Timing to .90mm and raised the pressure to 30psi.

Now I have really bad mid range rocks especially with timing set at .90mm

I retarted the timing to .87mm. still have rocks and mpg's seems to be down

should I drop the fuel pressure and raise the timing or try a diffrent advance spring or add shims

I have oil pressure gauges hooked up to the head and the oil filter mount
when cold the oil the oil pressure is around 60psi at idle and goes up to 80 and higher when when RPM is raised.
When warm at idle its around 5psi and maxes out at 30 psi.

Is this normal for oil pressure?

coke · Post by **coke** » Sat May 30, 2009 1:33 pm

How many miles on the engine?

New injectors are a good idea. I would take the pressure regulator out and knock it down some, that should take care of the "mid-range" marbles.

Any way to double check your oil pressure with another gauge? 8 psi on the top end is enough hold it together.

rabbit_man · Post by **rabbit_man** » Sat May 30, 2009 2:52 pm

Bentley says 28psi @ 2000rpm hot. Try adding an oil stabilizer like lucas or stp.

82vdub · Post by **82vdub** » Sat May 30, 2009 8:57 pm

Which location (head or oil filter) is the 5psi reading from? 5 psi seems really low to me - especially if at the oil filter. What weight oil are you running? This may be something that you may need to change your front intermediate shaft bearing and possibly the main bearings to bring your oil pressure back up.

MizPahPAH · Post by **MizPahPAH** » Sun May 31, 2009 12:19 am

Odometer reads 288k no Idea if any motor work has been done

I did pull the fuel regulator out and droped the pressure down to just above 20 psi and raised the timing up to .90 no more marbles.

I am running 15w 40 oil

I have oil pressure gauges on both the oil filter and the head.

Readings at idle when hot are between 5 and 10 psi
Readings top out at about 30 psi.

when its cold the pressures will go up to 60+ when I raise the RPM

MizPahPAH · Post by **MizPahPAH** » Mon Jun 01, 2009 10:06 am

The IP on this jetta has two nuts on the pulley side of the mounting plate making me uncomfortable trying to adjust the IP by ear.

so finding the timing sweet spot will have to be done mm by mm

The thing still ringing in my ear is 30 psi at idle from hagars post and the bocsh managment book..

do I boost the pressure back up and back the timing down to find best performance wil least marbles.

are marbles just annoying or are they bad for the engine?

hagar · Post by **hagar** » Mon Jun 01, 2009 11:16 am

MizPahPAH : are marbles just annoying or are they bad for the engine? hagars answer : BOTH.

Remember "pinging" in gassers ? a marble is very much the same. premature injection i.e injection before combustion chamber has reached ignition temperature. , the fuel piles up and goes off at the same time . That is a marble. . Now they come in many seizes that is why it so difficult to diagnose by mail.

hagar.

MizPahPAH · Post by **MizPahPAH** » Mon Jun 01, 2009 12:32 pm

with the fuel pressure at 30 psi idle 9 to 950 marbles were mix of high and low frequencey mostly low.. at between 1200 and 2000 rpm then cleared nice quiet and smooth on up to top end.

clear fuel line shows only a few tiny bubbles at higher rpm without a load

after a long streatch of running at 55 60 mph I come to a stop and i have rough idle for a few min / sec then clears up.

the one thing I have not checked is the screen and seal on the fuel sump in the tank.

going to run it as low as I dare and pull clean and replace the suction pipe seal.

He burned about a half a tank and trip odometer reads 220 miles

Thanks hagar / All !!

Op-Ivy · Post by **Op-Ivy** » Mon Jun 01, 2009 2:01 pm

Marbles mid range usually mean that your internal pump pressure is set too high. I know on my car I am not able to set it to Hagar's spec because I get the marbles as well.

Bring it down 5psi and see what happens. You will most likely need to do a lot of playing around before you lose the marbles.

hagar · Post by **hagar** » Tue Jun 02, 2009 12:11 am

MizPahPAH :: with the fuel pressure at 30 psi idle 9 to 950 marbles
were mix of high and low frequencey mostly low.. at between 1200 and 2000
rpm then cleared nice quiet and smooth on up to top end.

queit and smoooooth ? what do yo complain about ?. 12 Psig
indicates a worn pump , what I call marginal. .from memory 30 Psig
sound right so stay with that plus minus like Op-Ivy syggested.

Too low , and high pressure Plunger will cavitate. too high and Roller
ring tops too early and engine can not consume the fuel in an orderly
manner SO ? marble Magnums. we learn to dislike those here in the
forums. Less than 30 Psig and advance mechanism will not work correctly..At
say 5000 Rpm Roller ring must be hitting top stop. , period , read my
lips.. You need to pay attention to "TUNING" that means move the pump a
pencil line at the time. .What is the smallest move that make a
difference ? Loosen pump and think move , then tighten bolt see? known
as a "C" hair..

hagar.

MizPahPAH · Post by **MizPahPAH** » Wed Jun 03, 2009 5:46 pm

A bit of Gunk in the Sump..

Cleaned out the sump and I would say its a big diffrence.

Cant say that the marbles have gotten any worse but the Idle is definately higher and Smoother.

no more fluctuation at idle after a long run.

hagar · Post by **hagar** » Thu Jun 04, 2009 10:32 am

The way I get rid of Idle Marbles ? simple I just retard pump to it starts to "FOG" then very small movements to fog disappear. . Dynamic timing takes care of the rest of the RPM range.

hagar.

PS : moving pump is Static timing.

MizPahPAH · Post by **MizPahPAH** » Fri Jun 19, 2009 12:02 pm

Ran through my first tank of fuel. 45 mpg us

IP pressure set at 30 timing 1.00mm still a little noisy at Idle seemed to be coming mostly from cylinder #1
New Injectors second engine I have been running them in.

#1 injector at times has been weeping between halves.

So I pulled them all to check pop pressure 1800 to 1850 with some dribbling out the nozzle from #1

I have another set that I rebuilt last summer that pop at 1900 to 1950 no dribbles good spray patterns..
Thinking about putting them in??

When I first pulled the old injectors out "the ones that came with the car" cylinders 1 and 2 were dry, 3 and 4 all wet.

When I pulled them today same thing 1 and 2 dry, 3 and 4 wet
Compression test last time 400 + across the board going to do it again today.

Would this be a delivery valve problem?

MizPahPAH · Post by **MizPahPAH** » Mon Jun 22, 2009 12:58 pm

Compression is still the same from last time 400 to 460 all pretty even.

I set fuel pressure 1000 Pump rpm 2000 Crank rpm at 30 psi

at Idle its around 15 psi.

Is this correct???
I was setting it at 30 psi at 1000 crank rpm no wonder it had marbles

no matter how many times I read your'alls posts it didnt quite sink in

will find out tonight on the drive home if it is fogging
the only time is have been able to see fogging is at night in other peoples headlights

Former VWDieselParts.com Forum

Mid range marbles and oil pressure question

Mid range marbles and oil pressure question

Marbles.

Marbles.

Loose your Marbles.