Rhys Mann Posted September 4, 2023 Share Posted September 4, 2023 Just noticed that my oil pressure drops to almost the red line when I press the clutch down, is this normal? I usually have my mobile phone covering the gauge so not noticed this before! Otherwise she goes straight back up to the middle once in gear. Just thought I'd check in case there's a problem I need to look into! The Caterham is a Sigma 1.6 125, thanks in advance Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted September 4, 2023 Member Share Posted September 4, 2023 Does the engine speed drop much?Electronic or mechanical oil pressure gauge?Hydraulic or cable clutch?ThanksJonathan Link to comment Share on other sites More sharing options...
Rhys Mann Posted September 4, 2023 Author Share Posted September 4, 2023 No the engine speed doesn't drop and its a mechanical pressure gauge. Link to comment Share on other sites More sharing options...
Rhys Mann Posted September 4, 2023 Author Share Posted September 4, 2023 Hydraulic clutch Link to comment Share on other sites More sharing options...
PlastererPete Posted September 4, 2023 Share Posted September 4, 2023 What grade of oil are you using? And whats recommended? Link to comment Share on other sites More sharing options...
Rhys Mann Posted September 4, 2023 Author Share Posted September 4, 2023 Using Motul 5w 30 Link to comment Share on other sites More sharing options...
OldAndrewE Posted September 4, 2023 Share Posted September 4, 2023 Do you have an oil pressure warning light, does that come on? Link to comment Share on other sites More sharing options...
Rhys Mann Posted September 4, 2023 Author Share Posted September 4, 2023 No, there's no warning light at all on the dash! Link to comment Share on other sites More sharing options...
ChrisC Posted September 4, 2023 Share Posted September 4, 2023 Very strange, when the clutch is pushed the crank thrust bearing provides the opposing force to the pressure applied by the CRB. I have never heard of any crank thrust bearing issues in any modern Ford (unlike modern BMWs), so wouldn't know if this "old school" test is even valid, but a way to measure end float is to see if you can pull and push the main crank pulley (engine off obviously). Any physical moment is probably not a good sign. Link to comment Share on other sites More sharing options...
Rhys Mann Posted September 4, 2023 Author Share Posted September 4, 2023 It is strange! The oil was a bit low so have topped it back up to max to see if that makes any difference, could it be a faulty sender or oil gauge you think? Trying to see what the best way forward is without having to consider engine out job! Link to comment Share on other sites More sharing options...
OldAndrewE Posted September 4, 2023 Share Posted September 4, 2023 #10 you say "could it be a faulty sender" but higher up you say it is a mechanical gauge. There is no sender on a mechanical gauge, just a pipe connecting the gauge to the oil system Link to comment Share on other sites More sharing options...
Rhys Mann Posted September 5, 2023 Author Share Posted September 5, 2023 Ah ok! My mistake, it is a mechanical gauge do you think it could be a faulty gauge?Took her out last night and it only drops when the engine warms up, the rev counter also went a little crazy on one occasion when it dropped! So strange! Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted September 5, 2023 Member Share Posted September 5, 2023 Thanks for the extra information. I don't have a good explanation.Mechanical OPG:Put a finger on where the pipe enters the gauge. Do you feel any movement when you declutch? Similarly watch the piping in the engine bay: any movement there? Rev counter:I can't connect that to the mechanical OPG.Do you have an additional shift light unit?Check connections: instrument earth, ECU connections including earth, engine earths.Jonathan Link to comment Share on other sites More sharing options...
revilla Posted September 5, 2023 Share Posted September 5, 2023 Could you possibly post photographs of the front and back of the gauge so we know exactly what kind we are dealing with here please? Just a mobile phone shot from up behind the dash will do. Link to comment Share on other sites More sharing options...
K7 VCT Posted September 5, 2023 Share Posted September 5, 2023 Check the earth by the battery for the ecu...... Link to comment Share on other sites More sharing options...
Gridgway Posted September 6, 2023 Share Posted September 6, 2023 Check the run of the pipe from engine to gauge and see if there's anything squidging it or if it has a kink?How does the OP change with revs when hot and car is stationary?Is it only when moving out does it happen when stationary, out of gear and the clutch pressed? Link to comment Share on other sites More sharing options...
Rhys Mann Posted September 6, 2023 Author Share Posted September 6, 2023 Callum from Turn 7 got back to me so take it, it's not an issue?!"When you depress the clutch the engine revs reduce to idle speed. When you engage a new gear the revs will pick back up again. The oil pressure rises and falls with the rotational speed of the engine.Always here If you need us" Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted September 6, 2023 Member Share Posted September 6, 2023 That was my first question...Jonathan Link to comment Share on other sites More sharing options...
OldAndrewE Posted September 6, 2023 Share Posted September 6, 2023 #17 That does not quite add up for me. Are you saying the pressure drops significantly when depressing the clutch during a gear change? Link to comment Share on other sites More sharing options...
Gridgway Posted September 6, 2023 Share Posted September 6, 2023 Doesn't sound right to me either. Obviously the pressure varies with revs, but shouldn't go very low during a gearchange unless the revs drop to near tickover.I suggest getting the engine up to temp and see what the pressure does at tickover and then at every 500 revs up to 4k or so.Then maybe set up a cam to film the tacho and the OP gauge as you drive and see how it compares. Link to comment Share on other sites More sharing options...
Gridgway Posted September 6, 2023 Share Posted September 6, 2023 Also to add that different gauges have different levels of damping. The mechanical one might be very fast reacting as it were. Link to comment Share on other sites More sharing options...
Tom_Arundel Posted September 6, 2023 Share Posted September 6, 2023 Unless someone has changed it, Sigmas have electronic gauges.....they may look mechanical but aint! Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted September 6, 2023 Member Share Posted September 6, 2023 "Also to add that different gauges have different levels of damping. The mechanical one might be very fast reacting as it were."Andrew Revill has observed that his mechanical OPG reacts very quickly. And IIRC that air in the pipe to the gauge affects damping.Jonathan Link to comment Share on other sites More sharing options...
Rhys Mann Posted September 7, 2023 Author Share Posted September 7, 2023 Here's a video of what's happening, when i engage the clutch you can see the pressure drop and then goes back up when in gear, normal?https://vimeo.com/861896635?share=copy Thanks for all your help I really do appreciate it Link to comment Share on other sites More sharing options...
Dixa1225 Posted September 7, 2023 Share Posted September 7, 2023 I have owned two Sigma cars. That gauge action is normal for this engine. It is also the original electic gauge & sensor. Nothing to worry about here. Link to comment Share on other sites More sharing options...
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