30 replies to this topic

[phildward]

I’m working towards starting my car for the first time in 20+ years.  I've had the head off and checked the valves and bores.  I've replaced the oil, primed the oil pump, filled and fitted a new oil filter.  The starter is new and the battery from a 1.8 litre Golf and fully charged.  I can't crank the engine via the ignition key because of some rodent damage to the wiring harness.  However I wanted to check for oil pressure and the engine turns over nicely with the engine earthed and a positive jump lead held on the positive terminal of the starter.

 

I connected an ohmmeter between the terminal of the oil pressure switch and the engine, it showed open circuit.  I then cranked the engine expecting to see a change but nothing happened .  It could be I don’t understand how the switch operates?  I’m reluctant to start the engine before I have pressure; any tips appreciated.

 

I have read this thread http://www.theminifo...= oil pressure but not seen an obvious solution.

 

The switch I have is GPS133 seen here http://minispares.co...ure switch.aspx .  I see also on the same page there is an oil priming plug seal.  Could I be missing a trick here?

 

 

 

 

 

 

[Swift_General]

You are right to not run the engine until you have confirmed oil pressure. If the engine hasn't been run for a while it may take some time to get oil pressure (more than a crank of a few seconds). How long have you turned the engine over for? Did you have the plugs out? How did you prime the oil pump? Of course the switch may be defective.

Edited by Swift_General, 11 February 2017 - 03:16 PM.

[phildward]

Thanks Swift_General, primed the oil pump by removing the oil filter and cranking until there was a steady flow of oil into a tray. Filled the filter with oil and cranked the engine for a while with the plugs removed.  Replaced the plugs and cranked again.  Left the car for a few days and went back with the ohmmeter.  No change to the oil pressure switch resistance on a good cranking, didn’t time it but the jump leads warmed up.

Edited by phildward, 15 February 2017 - 06:43 PM.

[Cooperman]

Best and safest thig with a new engine or one which has not been run for a long time is to fit a pressure gauge. They are not expensive when considered against the damage that can be done if an engine is run with no or low oil pressure.

[phildward]

I did wonder about a pressure gauge, I'll take a look on the internet.  I guess the problem will be getting the correct threaded adaptor?

[Cooperman]

Just call Mini pares. They do a complete kit for a sensible price.

[Swift_General]

If you are getting oil from the oil filter housing with the filter off then clearly there in oil in the pump and the pump is pumping so with a filter on you should have some pressure. I'd suspect the switch. Even if a replacement switch shows oil pressure Cooperman's suggestion is a good one still as a gauge will give you some indication of the condition of the engine given that it hasn't been run for so long. One other thought. I would check the relief valve. If this is stuck open then you would have next to no pressure, but would still likely get some oil from the filter housing without the filter off.

[Spider]

The Switch should be Closed with no pressure, ie, without the engine running. If you have an Open Circuit before cranking, the Switch is cactus.

[phildward]

Thanks Cooperman and Swift_General I've checked the description for GPS133 at Mini Spares:

 

Fits every A series engine from 1959-1996 (except twin point injection minis)

they have a different switch GPS135 and also have a transducer for oil temperature (YCB100320).

These original type oil switches came on when oil pressure dropped below 7-10lbs

 

It appears the switch should switch to open when it is subject to 10 psi of oil pressure; new switch on order.  I'll also get a pressure relief valve washer and check the valve as the flow from the oil filter housing was weak by comparison to modern engines.

 

I'll report back on the final fix.

Edited by phildward, 15 February 2017 - 06:44 PM.

[phildward]

The Switch should be Closed with no pressure, ie, without the engine running. If you have an Open Circuit before cranking, the Switch is cactus.

 

Thank you, thats the conclussion I came to having read the description at Mini Spares.

[phildward]

Right; removed oil pressure relief valve but not sure how to decide if it is good or not. Looked OK and moderate pressure was required to compress the spring when refitting the cap so assumed it's OK????

 

Removed plugs and oil pressure switch and cranked the engine; a good flow of oil came out of the switch location hole.  I’m assuming all is good but will test again when the new switch arrives.

 

[phildward]

New switch fitted and the amber oil light comes on.  Crank the engine with no plugs and the oil light eventually goes out.  Crank the engine in with the plugs in and the oil light remains on.    I’m confident when the engine fires it will generate oil pressure.

 

The original question has been answered however the engine appears slow (by modern standards) to generate oil pressure.  Is this normal for an A Series engine or should I be looking for other issues?

 

 The battery is fully charged and from a 1.8 Golf.  The oil is clean 10/40 semi synthetic with a new Unipart filter.

[cal844]

New switch fitted and the amber oil light comes on.  Crank the engine with no plugs and the oil light eventually goes out.  Crank the engine in with the plugs in and the oil light remains on.    Im confident when the engine fires it will generate oil pressure.
 
The original question has been answered however the engine appears slow (by modern standards) to generate oil pressure.  Is this normal for an A Series engine or should I be looking for other issues?
 
 The battery is fully charged and from a 1.8 Golf.  The oil is clean 10/40 semi synthetic with a new Unipart filter.

The issue you are having is that the oil is too thin, 10/40 is good for an automatic engined car, however you NEED 20/50 in a manual transmission

[phildward]

Thanks cal844, did wonder if that may be the advice.  However I’m fairly certain that this car has always been fitted with 10/40 from new.

 

Is 10/40 the correct oil for an A+ engine and transmission?  I know 20/50 is correct for earlier cars.

[tiger99]

Depending on who you believe, 20W40 may be correct for manual cars. If so, I have been wrong as I generally used 20W50. Did it do any harm? No way of knowing, but it may have hindered performance and fuel economy slightly.

I doubt that the gade of oil is the problem here. You really NEED a pressure gauge to tell you the whole truth alongside a switch which only tells you if the pressure is above 10psi, which is far too low if the engine is running.

You may not reach 10psi at cranking speed, plugs in. If you crank it well with the plugs out there will be sufficient oil in the bearings to put the plugs back in quickly, give it another quick crank and then briefly fire it up. If the gauge climbs immediately (1-2 seconds) relax. If not, switch it off and investigate.

Oils are designed to remain in the bearings for quite some time to allow engine start without damage.

However it would not be unreasonable for up-market cars to be fitted with an electric priming pump, although I suspect that none are, unlike trains and such like. You pay well over the odds for something big and flash and get the same cheap tat in the lubrication system as a bottom of the market Hyundai Getz....