1992 Jetta Oil Pressure light flickers

[robsjetta]

1992 VW Jetta (base model) 1.8L engine, 5 speed, no A/C, 275,000km (171,000 miles), using 10W30 oil.

This problem began several years ago only in very hot weather, engine temp at the point the cooling fan would turn on and engine idling (ie. when stuck in traffic on a very hot/humid day). Increasing the RPM slightly would turn the light off. A nuisence but I have tolerated it as the car is not driven very much anymore.

Now I find the light flickers most of the time especially when cold, accelerating and engine RPM between 2000 and 3000. After engine warm up the problem seems to subside or even go away until the engine temp is very warm thus the original problem begins.

Is there any way of knowing by these symptoms if this could be the pump or a pressure switch? Any way of diagnosing which part is at fault. Any suggestions would be helpful. Any way to know for sure?

Thanks,

Rob

[16v mad]

well for a start your using the wrong oil..you should be using 15/50 or 20/50.......10/30 is like pi$$ water,you slowly killing your engine

[robsjetta]

Have been following manufacturers requirements all these years (bought car new). 10W40 in summer and 10W30 in winter. Those are the specs for cars in Canada. Granted as the car ages the viscosity should thicken. Have thought about trying it but thought it is required more if you are burning more oil which the car is not. Definately worth trying before purchasing and replacing the pump.

Thanks 16v mad.

[16v mad]

thats interesting,id of thort they were all the same as there all the same manufacturer,have you had the oil pressure checked,maybe taking the sump off and cleaning the oil pick up would be a good idea,but id certainly have a mechanic test the oil pressure with a guage

[robsjetta]

Looking into getting my own oil pressure gauge and testing it. Need to special order one but considering using one of those dash mount gauges although I don't know how accurate the reading would be.

Cleaning sump is another consideration but would do that at the same time as if the pump was to be changed or when all diagnosis lead to the pump. Have limited time to do the work and for the car to be down so I need to do as much at once as possible and wouldn't want to be taking the oil pan off twice.

Checked the pressure switch this past weekend. Switch seems fine. Actually does start the buzzer alarm when above 2000 to 2500 RPM and over that for a few seconds. As the light is flickering it is never on long enough for the buzzer to go on.

The car had a good driving run on the weekend, about 160 km (or 100 mile) and found the light flickering was inconsistant to engine temperature. I have found that it is definately flickering under load (acceleration, uphill, etc.) Can't figure out why it would only do this under these conditions. The only thing I can think of is a possilbe wiring issue where it may be shorting/go open when the engine twists/torques under these conditions. Thus I have to get a second body to watch the dash while I jiggle the wires to see if there is a wiring issue and rule that out to.

I'll keep you posted.

[16v mad]

if the buzzer goes off at 2k and over its triggered by the sender with the white cap and yellow wire,this is the high pressure sensor 1.8 bar,if you take the wire off and earth it and start the car,rev it a few times to say 4k and the buzzer stays off the wiring is ok,when you drive the car under load you create more strain on the engine and friction,everything has to work harder especially the oil pump
its funny really over the years i have talked to many ppl about oil pressure warning system and 99% of them say the senders must be faulty and replace them to find its not that,i always say if the light or the buzzer come on check the pressure first,i would do it with a propper one tho not a dash mounted on,the real thing will be more accurate,not sure how much they cost but ask a few garages how much theyl chek it for you,there are a few things hat go wrong on these pumps.the releife valve,strainer block and wear,replacing it would be a good idea there approx 36 quid and 4 for a sump gasket

[robsjetta]

Thanks for your input 16v mad. I really appreciate it. I am planning to buy an oil pressure tester but have to have it ordered in. About $59 CDN. The oil pump here at best is about $115 CDN.

I had a little time to look at a few things this evening before I received your reply. As I have seen an increased oil leak the past week, I had found (and this seems very odd to me) that a leak is occuring out of another sensor (assuming it is the low oil pressure sensor) that has a blue/black wire connected to it and is located just above the cooling hose flange beside cylinder #4. The odd thing is the leak is coming from between the sensor's connector and the epoxy filler. It only leaks when the engine is running and I found it by fluck after taking off the black rubber boot which was filled with oil. I had known about a tiny oil leak off the rear side above cylinder 4 on the rocker cover but it wasn't enough to reach the ground. The plan is to have it replaced also and will be checking all valve clearances to and hopefully not find any damage due to the oil pressure issue.

[16v mad]

yup, it sure is the low pressure one with the blue and black wire and this is a common fault im hearing of it more and more now of these oil pressure senders leaking,just as you discribe it,there not too expensive to replace and sounds like thats the fault,fingers crossed eh!thing is yours is a 1992 model so it will have hydraulic cam followers so the valve clearenses are self adjusting,i suppose you could have a look for wear on the cam but id say it will be ok,i have a 16v golf and i left the oil filler cap off once and i did 30 miles before i realised something was wrong,it had spued oil out all over the place and no oil in the sump and its fine its still running like a dream
keep us posted anyway

[robsjetta]

Mission accomplished.

Finally replaced the switch this past weekend, although other parts stores didn't have the right one so I had to get it directly from VW. Couldn't believe the price for such a thing, $25CDN. I know VW prices on parts went up but WOW! To add insult to injury the parts associate said the price was $8, 18 months ago. OUCH!!

Checked the oil pressure seems fine as the pressure went down to between 10 to 15 PSI (0.69 to 1.03 bar) at idle, when the engine was fully warmed up. The low reading was about 30PSI (2.07 bar) when first started and cold.

Had a long drive with the car today and although it isn't a very hot day here today the car did idle in traffic a lot and didn't see the light flicker at all, when the engine temperature was high. This fix may have licked that problem too.

Changed the valve cover gasket and looked at the cam. It is like new. I couldn't believe it.

Hope to keep this car going as long as I can. I don't think I'll ever get anything as good as this ever again. VW really built a good car at this time. I hope what is new and coming now is just as good.

Thanks 16V mad for all your help and insight.