Oil light blinks when i get off the highway

SLawson · Post by **SLawson** » Mon Mar 08, 2004 1:06 pm

Hey all. I have a 1776 in my bug and after i drive on the highway for a period of time (say......25-30 min), my oil light comes on. What's the problem? Is my engine getting too hot or what? Please help. The only cooling system i have is the usual. The fanshroud, cooling tin, oil cooler, that's it.

Eaallred · Post by **Eaallred** » Mon Mar 08, 2004 1:30 pm

VW stated it as "normal" for the oil light to flicker at idle after a heavy load was put on the engine (like driving on the highway). Coming on steady without flickering means the engine is getting too hot.

Post by **Marc** » Mon Mar 08, 2004 1:39 pm

Is the engine compartment well-sealed so that no hot air from below can come up and be recirculated? Freshair hoses are intact and connected at the heater boxes? Do you have a louvered decklid? Doghouse cooler with correct wider fan? What weight oil are you running, and what's the RPM & ignition timing at idle? What's the ambient temperature when this happens?
It is considered "normal" for the oil pressure at hot idle to drop low enough to make the warning light flicker when you've just pulled off the highway and the cooling fan speed drops 'way down (there's a good deal of residual heat in the engine under those conditions that takes a few minutes to dissipate) but it should go out if you raise the RPM slightly, say to 1000.
If you suspect it's too hot, a simple test is to grab the dipstick. If you can hang on to it indefinitely it's probably below ~140°F at the handle, indicating that the engine temp isn't extreme.
Low oil pressure at hot idle is typically due to loose clearances in the pump or in the engine itself and/or too light of oil for the conditions.

Honda's Killer · Post by **Honda's Killer** » Mon Mar 08, 2004 2:26 pm

What kind on pressure are you getting when you fire it up in the morning. Before I exit the freeway, I slow down to about 55 and just cruise for a few miles. might help

SLawson · Post by **SLawson** » Tue Mar 09, 2004 11:18 am

Well if it's considered normal then good. When i raise my rpm slightly it does go away. I have never tried holding the dipstick. Maybe i will next time just to be sure its not getting too hot. Thanks for the input guys.

chopped65 · Post by **chopped65** » Tue Mar 09, 2004 9:46 pm

I noticed mine doing this for the first time also with this hot weather after prolonged highway driving. I have a 1641. It does go out and all when I raise the RPM's. The oil pres. also reads really low on the gauge at hot idle but reads normal most of the time. I run 30wt oil. Should I try 20w50?

albersondh · Post by **albersondh** » Tue Mar 09, 2004 11:23 pm

Hey thats funny I just got on here to ask just about the same question. My oil light does the flickering thing too in the same sanario. I have a VDO gauge and sender. When the light flickers once I get off the freeway Im reading less than 5PSI this worrys me. When I built the motor I checked and double checked all the bearings for proper hydrodynamic clearance so thats not it. The one thing I did do was to turn the oil pump cover so that the old swirly marks from the gears were no longer over the gears. I dont know it seemed like a good idea less leakage? After doing this and installing new bearings it does the low oil pressure thing. So tonight I pulled the pump cover to check things out. I took the old cover and DA sanded it with 220 to remove all the swirlys. I reinstalled it and Im waiting for the permatex to cure now. Ill let you know what happens.

Post by **Marc** » Wed Mar 10, 2004 6:03 am

Removing the "swirlys" is good, the cover should be as flat & smooth as possible for minimum end clearance on the gears...which is why you should also use only the thin gasket, put on dry, between the pump & cover. Permatex is a bad idea here, unless you're only talking about a trace application of the spray-on kind.

Guest · Post by **Guest** » Wed Mar 10, 2004 1:27 pm

would changing the weight of the oil do anything?

Post by **Marc** » Wed Mar 10, 2004 1:38 pm

Anonymous wrote:would changing the weight of the oil do anything?

Yes, it would (which is why I asked what weight he's running - still waiting for the answer).

SLawson · Post by **SLawson** » Wed Mar 10, 2004 7:57 pm

Marc wrote:Yes, it would (which is why I asked what weight he's running - still waiting for the answer).

Whoa, sorry Marc. I must have missed that question. I'm running 20w50. I used to run straight 40w. Should i go back? Some old guy gave me a empty Shell oil container that had like 80w oil on it's label. It's supposed to be for use on airplanes but he said it's good for vw's. I've been looking for that damn oil everywhere but can't find it.

albersondh · Post by **albersondh** » Wed Mar 10, 2004 11:05 pm

Ok after resurfacing the swirly marks off the oil pump cover and resealing with a small amount of permatex "which I know is not correct". I went on the same route on the freeway that I did when my oil light started to come on at the same time of day. All variables being equal except the ambient temp was about 5 deg F cooler today. Not only did my light not come on but my oil pressure read almost 10 PSI at idle after getting off the freeway the lowest it got was 7 PSI. Im also running Kendal in a 20/50 weight. So Im happy now. Hey if all else fails check the pumps gear back lash and resurface the pump cover.

Post by **Marc** » Thu Mar 11, 2004 5:39 am

SLawson wrote:... I'm running 20w50. I used to run straight 40w. Should i go back?

I'd stay with the 20W-50. It's actually heavier than you should need on a tight engine but the reality is that unless you have a new case you probably need it to make up for pressure lost at worn lifter bores, at least in warm weather. With straight 40W you shouldn't leave the driveway on a cool morning without idling for about 5 minutes, with the multi-weight it's good enough to just go easy for a few.
As for 80W, or STP/PowerPunch "viscosity improvers", if they're the solution you've got a serious problem. The oil-pressure control system's primary purpose is to regulate oil temperature, and artificially jacking up the pressure will confuse it - stiffer springs will delay warmup, heavier oil will cause the cooler to be bypassed more of the time and the operating temperature can actually increase.

Guest · Post by **Guest** » Thu Mar 11, 2004 11:41 am

Ok, thanks for the advice Marc. I'll stay with 20w-50.

(BTW this is SLawson. I just didn't feel like logging in.)