Low oil pressure

[ed124]

Hi,

My new '77 Spider seems to have an oil pressure problem. The oil pressure gauge only goes up slightly after starting the engine, then goes back to (near) 0. I replaced the gauge in the dashboard with another one, with the same result..

I then thought (hoped) then there may be a problem with the sending unit (see topic in General maintenance), but I did some more tests today and the oil light starts to flicker sometimes at (low) idle speed, when the engine is hot. I asked my local garage who thinks the oil pump does not work properly, and suggested to use really thick oil to avoid having to replace the oil pump.

What do you think, is this a good suggestion? Are there still other things I should test first? I guess replacing the oil pump means taking out the whole engine

Ed

[narfire]

It could be something as simple as a clogged pick-up screen on the bottom of the oil pump. Will have to lift the engine a bit to get the pan off to have a look.(undo the engine mounting nuts and jack at the bell housing) My VW just had that problem, cleaned and no issues.
Have you considered an after market mechanical oil gauge? I bought on several years ago for about $40 or so and had the thing in in about a hour or less. Real easy to do with a complete kit with tubing and flare fittings included.
Chris

[ed124]

Thanks for your clear answer.
I hadn't yet considered buying a new pump, because I thought you would have to remove the entire engine to replace it. But if it only takes and hour to do by lifting the engine, it's definitely worth considering!
Cheers,
Ed

[narfire]

A bit more clarity...installing the mechanical oil gauge was about an hour or less.
Getting the oil pan off was longer..I believe we had to loosen the exhaust manifold, engine mount nuts and transmision mount as well. There are baffles in the oil pan that help preven the oil sloshing around too much,the pump pickup is tucked under a baffle. That is why one needs more clearance from the cross member. I used an impact drill with a 1/4 inch adapter to get the half a zillion pan bolts off .
Ramps work well but remember, do it safely, block the car tires etc.


Chris

[So Cal Mark]

pressure is created by the clearance on the crankshaft bearings, so even a good pump can't create pressure if the clearances are excessive. The first step is to use a mechanical gauge to accurately measure the pressure

[Fiatmonkey]

I read once about increase the oil pressure by shimming the oil pump or the spring in it. Apparently that increases the flow somehow.

But if you've never done anything with your oil pump or oil pan, I'd put money on some simple maintenance to fix it. By that I mean you have sludge in the oil pan and your pump can suck that in. I'd just pop the pan and remove the pump for inspection. Pumps are pretty easy to look into.

Now, cheat and see if it's pumping ok... put some oil in a 5 gallon bucket then put a drill on the pump shaft and begin spinning. If oil spurts out slowly the pump doesn't work too well. If it rockets out like "Old Faithful" then your okay. Just clean the pan and replaces the associated gaskets.

This in total should take like 1/2 a day.

Easy pan removal I use is..
1. Put on ramps
2. take of nuts on bottom side of engine mounts
3. gently (using a wood block on your jack) lift the motor about 1-2 inches
4. put shims under engine mounts (chunks of 2x4 work great)
5. remove pan and pump

Hope that helps.

[DUCeditor]

When I bought my `77 in `88 I observed with great concern the same low reading. At the time I had as a resource a mechanic who learned his trade in Rome (yes, his name was Tony) and who knew Fiats backwards and forwards.

His words when I expressed my concern were basically that the gauges read that way on almost every Fiat from that period and that there was nothing to worry about. "Its likely been that way since new and it hasn't hurt the motor yet" said he referring to the car's then 76,000 odometer reading.

Well the cars odometer now reads 120,000. I long ago stopped worrying. There s also a low pressure warning light. If that ever comes on I will most certainly take note.

Was it a coincidence that Fiat removed the pressure gauge from the Spider's dash a short time later? I think not.

-don

[ed124]

Thanks for all the advice.

I did not worry too much about the low gauge reading, until I noticed that the light goes on (and off, it sort of flickers) when the engine is hot, running idle and the car is leaning a bit backwards. As soon as I drive on the light goes off.

This happened with the original gauge and light, and now also with the new one, which made me worry that it is not the sending unit either (I heard they're separate, light and gauge). The car is otherwise running fine, and the engine sounds fine too, no strange noises as far as I can tell.

What do you think about the suggestion of my garage to put in thick oil as a temporary solution? Or should I stop driving and really solve the problem?

[DUCeditor]

What do you think about the suggestion of my garage to put in thick oil as a temporary solution? Or should I stop driving and really solve the problem?

I do that. I use 15-50 and as the Summer progresses and the temperature rises I add STP to raise the viscosity even higher.

In the end I have no doubt that the issue is the bottom end bearings. But my motor continues to run so sweet that I just live with it and will until she starts to burn oil enough to smoke. Then I'll have her entirely rebuilt.

My own thoughts on this is that when a car is as old as these -- especially if it has never been rebuilt -- the rules followed with a newer vehicle no longer apply. Sort of like with my own aging body.

-don

[narfire]

As Mark mentioned,take it to a shop and have them check the pressure mechanically or install a mechanical guage yourself. Here it gets hot in the summer(80-105 deg F) so I run 20-50 in the engine and have pressure of between 55 and 35 psi depending on startup and temp of the engine.
Knowing for sure what the pressue is will give you a piece of mind and you can then decide what the next step will be instead of guessing and wondering.
Then you can sip your Heiniken in comfort

[maytag]

as your engine ages, the tolerances increase, meaning less pressure is built as the pump forces oil through the small passages.
Using thicker oil will make it harder to force the oil through the smaller passages, building more pressure at the pump, making the gauge read a little higher.
But is that really any better for the motor? Not in most circumstances. it's an artificial bump in the pressure. Another cause of low oil pressure can be passages with inconsistent flow due to sludge build-up, sludge on your screen, etc etc.
You can sometimes use thicker oil to quiet worn bottom-ends. But making the noise go away doesn't necessarily equate to better protection.

I AM a believer in "high mileage" oils. Mobile1 has a great product out that is specifically for motors with over 75k miles. They have an additive that helps protect cams & such (phosphor? zinc?) and they have added detergents that'll help clean-out years of dinosaur build-up in the oil passages.

I shouldn't say this, BUT: back in the day, there were two tricks that were used frequently when an older motor started to tick from lifters no linger getting enough oil to pump-up.
1) we'd run 4/1 ratio of oil/ATF for about 500 miles. The ATF will break-down the deposits in the motor and allow oil to flow again.
2) a pint of Marvel Mystery Oil in the crankcase at every oil-change.

I make no claims about these two "tricks", other than I've used both in the past with some fairly phenomenal results.... but you're of course responsible for what you put in your motor and where! (wow... that sounds dirty! )

[ed124]

Thanks all,

I will find out the real pressure first then decide what to do next. I will keep you posted.

And I think I'll have some Heineken anyway

[4uall]

here is an interesting video
http://www.youtube.com/watch?v=8f2fcbTh ... ure=b-vrec

[majicwrench]

What weight oil are you running now?? And really nothing wrong with light flickering at hot idle. Would be nice if it didn't but such is life. LIkely a combination of worn bearings and a worn pump. I would not add anything to oil but oil. How does it run?? If it runs poorly or choke stays on too long can dilute the oil with fuel, thus becoming thinner. I would bet you have changed the oil with same flickering light? Stick a gauge on it if you want, but keep driving it and have fun with it.
Keith

[ed124]

It's got standard 10W40 oil right now. But your suggestion of dilution could be relevant, because I have had some trouble with the choke staying on and I've driven around with rich mixture for a while. The engine runs fine and sounds normal as far as I can tell.
I will check the pressure anyway and see what's next, but I guess I shouldn't become too fixated on it