Hi my felicia 1.3 is running well but im concerned about the oil pressure. When the engine is cold there is about 40-50 psi at 1500 rpm and with the engine hot there is only 10 psi at 800rpm. Isnt this too low or its safe ?

Sounds OK to me.

Haynes specified 3.5 bar minimum at 1500 rpm, mine is like 45 psi when cold

I don't have Skoda figures for min oil pressure, but as long as you have pressure at idle that's ok. At the point where oil pressure rather than flow really matters, in the main bearings, the pressure is probably around 100 bar at 1_500; the 0.5 bar you're missing is less than the accuracy of your gauge!

 

NB Ricardo, I'm arguing that if you don't have oil flow then infinite pressure is useless; Also that pressure at the gauge sender is a very different thing to pressure in the bearings, and as long as you have good volume flow you should have good pressure in the bearings because that pressure is generated by the volume flow and spinning shaft rather than by the oil pump discharge pressure.

I don't have Skoda figures for min oil pressure,

That's a good start, considering that figures are all that matter in this topic...

...but as long as you have pressure at idle that's ok. At the point where oil pressure rather than flow really matters,

No, Ken, flow does matter. No flow, no pressure. Not to mention it's not OK to roll two metallic surfaces on the same oil.

...in the main bearings, the pressure is probably around 100 bar at 1_500; the 0.5 bar you're missing is less than the accuracy of your gauge!

Just for the record, Felicia does not have an oil pressure gauge. Only a low pressure oil switch.

 

NB Ricardo, I'm arguing that if you don't have oil flow then infinite pressure is useless;

Wow, two rows above you said exactly the opposite...

Also that pressure at the gauge sender

As I've said before, there isn't any 'oil gauge sender' on Felicia.

...is a very different thing to pressure in the bearings, and as long as you have good volume flow you should have good pressure in the bearings because that pressure is generated by the volume flow and spinning shaft rather than by the oil pump discharge pressure.

Since the oil pump on Felicia is a volumetric pump, we can't really talk about any 'discharge pressure'.

Haynes specified 3.5 bar minimum at 1500 rpm, mine is like 45 psi when cold

Wrong. It's minimum 3.8 bar (55 psi) at 3000 rpm and oil temperature of 80 C.

Ricardo, where to start?

 

I did not say that a Felicia has an OP gauge as standard. Since the OP apparently has one, I presumed the usual installation using a tee piece or dual function sender at the standard location.

 

As a point of physics you're dead wrong about pressure and flow; given a sufficiently powerful pump you can get near infinite pressure with no flow on a blocked channel.

 

Also you haven't actually bothered to read what I said; point can mean more than one thing. In "the point where oil pressure rather than flow really matters" it means "location" or are you going to claim that the thin film of oil in your main bearings is the only thing that keeps the cast iron (or steel) and bronze (or white metal) of the crankshaft and bearing apart? Oh wait, that's another of your statements proved wrong; the oil is in contact with 2 different metals there!

 

Next, you appear to be ignorant of hydrodynamic pressure, which is where the 100 bar I quoted came from, and why I suggested that half a bar at the sender doesn't matter; because it's only 0.5% of the pressure in the bearings!

Wrong. It's minimum 3.8 bar (55 psi) at 3000 rpm and oil temperature of 80 C.

I will take 80 degrees to be after about 2 minutes or 3 of driving, if so i think my pressure is within spec then at 3000 rpm

Next, you appear to be ignorant of hydrodynamic pressure, which is where the 100 bar I quoted came from, and why I suggested that half a bar at the sender doesn't matter; because it's only 0.5% of the pressure in the bearings!

 

Coming from you, the opinion is an oxymoron. I simply don't care about your theoretical, generic, off-topic blah blah. This topic is about minimum oil pressure on Felicia. Since you admitted that you don't have any clue in that regard, what is the practical value of your comment? It boggles my mind you have tens of thousands of such replies. By the way, Wikipedia is wrong on many subjects. So is Haynes.

I too have a Felicia low oil pressure problem. With hot oil, the pressure at idle falls to 8 psig. This is low enough to cause the oil pressure warning light to blink, so I plan to drop the sump and investigate. (The pressure hot at 1800 rpm is but 30 psig, i.e. well below the minimum suggested in the H-book, though I suspect that their minimum figure may be excessively high at ~ 54 psig).

From my own past experience (albeit with a different engine) I know that sometimes a "tired" oil pressure relief valve spring can make a big difference, so that is high on my list for checking. Most annoyingly, neither of my H-books offers any tolerance figures for this spring. Can anyone tell me the free length of a new spring?

(136 petrol injection; my measurements are taken using a ordinary Bourdon-tube pressure indicator connected to the oil pressure switch port. BTW, can anyone tell me the function of the nearby crankcase port which I have blanked with a 21mm hex head plug?).

Edited 2 December, 20169 yr by Skodle

I doubt there is a weak spring on the oil pressure relief valve. The valve is set to open at 5.8 bar, so...

It's more like worn crankshaft bearing(s). Depending on how well previous owner(s) maintained (oil used, change intervals) and drove (hard, overheated) the car, such thing can happen sooner than normal.

 

The port in the block slightly above oil pressure contact is an additional drain / flush plug for the coolant in the block.

Thanks, RicardoM - yes, that is my fear! In your experience, are the main crankshaft bearings more likely to be the problem than the conrod big end bearings?

I still want to check the relief valve spring, so grateful if anyone can let me know the length of a new one.

I meant the blanked oil gallery port over to the left - just curious to know what purpose it serves.

Thanks, RicardoM - yes, that is my fear! In your experience, are the main crankshaft bearings more likely to be the problem than the conrod big end bearings?

Based on my findings it's the conrod bearings that fail more often. Not that it would matter too much. A proper repair means removing the crankshaft for inspection anyway.

 

I meant the blanked oil gallery port over to the left - just curious to know what purpose it serves.

Depending on the equipment installed or not on the engine (A/C, PS) the block is slightly different and some holes are blanked or not machined at all. But generally speaking, on the left side (see photo) there are mounting holes.

I checked, after about 7 minutes of driving, i revved to 3000 rpm, it went to 50 psi.

I checked, after about 7 minutes of driving, i revved to 3000 rpm, it went to 50 psi.

I have experienced oil pressure problems with a few different bit on the 136 engines, oil pickup pipe could be blocked on the strainer mesh, the pickup pipe bolts to the oil pump via 4 bolts and no gasket and the mounting surface can warp slightly allowing the pump to suck a bit of air, the relief valve may have a bit of debris stuck under it allowing pressure to escape and the oil filter itself could be partially blocked.

first I would change the oil and filter and see if that improves the pressure, if not then sump off and check the strainer mesh and check that the sump is not tight against it, (lump of Plasticine is useful for this, then check the relief valve and pickup mounting face for flatness.

also I have seen the jet for the timing chain lubrication fall out and this leaves a large hole that oil can flow away through. if all is good so far then main bearing caps off to check condition and clearance. 

If there's oil starvation and the strainer mesh is clogged, the oil should look like mud. I suggest that before changing the oil use a n oil flush solution to wash all the crap. Then drain the oil, remove the oil sump, remove the pickup pipe and check what felicia16v mentioned. If the flatness is OK make sure you torque all four M6 bolts at 8 Nm evenly. Clean the pickup strainer if dirty. Look in the oil sump and in the drained oil for metallic flakes or other debris.

 

felicia16v

Your specific, first-hand knowledge is very important and appreciated. I have only one small request. Please specific when your findings come from Felicia/Favorit rally cars driven in rally conditions. Normal driving of stock Felicia/Favorit cars is nothing close to rallies. Thanks.

I've come across all those symptoms on road cars during the 23 years working at a skoda specialist as well as rallying them. Although the pickup pipe mounting is usually warped from overheating the engine/oil.

I've not seen many standard cars with worn out bearings enough to drop the oil pressure that much I'll admit but once you start using higher rpm the std bearings do fail quite quickly.

On the other hand I've been to cars that have blown away headgasket and been driven until the spark plug leads melt off and the engine has been fine after a head skim for many thousands of miles.

I don't like using or advising the use of oil flush as it sometimes just loosens the crap which then breaks down into the fresh oil and blocks the timing chain jet.

I don't like using or advising the use of oil flush as it sometimes just loosens the crap which then breaks down into the fresh oil and blocks the timing chain jet.

Speaking of which, how can we diagnose if that jet is blocked? I mean without exposing it.

Also what damage did you find from that blockage? I'm asking because I've seen lately many timing chains worn prematurely and so far I've put the blame on poor quality of parts (although not Chinese).

Edited 3 December, 20169 yr by RicardoM

You can't easily although we use an air powered oil pump to dispense bulk oil so we used to remove the distributer drive so we can see the timing gear and pressurise the oil system via the air pump on one of the external access plugs. Can just about see if anything is squirting out of the jet. Always check the jet with a needle or wire when the chain is removed anyway

Its soon time for my routine oil change, like 600 miles left. The engine does great in my opinion, i only add about 500ml of oil in about 2.5k miles, i use 15w40 with anti drain back oil filter. I will use an oil flush as you say, i used it also in the last oil change

Always check the jet with a needle or wire when the chain is removed anyway

Roger that.

When the car is hot at operating temp pressure is 15psi at 900 rpm idle and 45psi at 3000rpm

Im using an ebay gauge, maube its not that accurate, its called dragongauge i think made in china...