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Esprit Turbo project car - part3 - the further continuation - Page 187 - Esprit 'Project & Restoration' Room - The Lotus Forums Jump to content
Lotusfab

Esprit Turbo project car - part3 - the further continuation

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7 minutes ago, Lotusfab said:

Had it running at idle for some minutes begfore I bottled it. Didn't really lift the revs above idle. Run it about four times.  I may have another go after pumping oil through the Turbo pipe and time it.

Could the pressure relief valve in the oil pump be stuck open? Or is it just there's no oil in the pump and it needs to runs slightly above idle for some time?

I favour the latter notion. It can be tempting to chase unicorns when under stress, though always good to keep an open mind. Stick to fundamentals until the way forward becomes clear. If the cams/tappets are not new (i.e. broken in already) and all internals are well lubricated as appropriate upon assembly there is no great cause for worry about somewhat lengthy slow running under no load.

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Just had another go. I pumped some oil back through the Turbo feed. After about 30 secs got this.I thought job done. Until the engine cut. When Inrestarted no oil pressure!IMG_0102.thumb.JPG.e4488ac4ad976f04e484d7d71b7944f1.JPG

?????

I ran the engine for about 5 minutes.Could it be the pick up pipe?

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Actually must have been longer. Could the thermostat have opened and pressure went to zero because the cooler was filling up?

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Most likely must be an air leak between pick up and oil pump,  Are you 100% sure olive is well nipped-up?   Cant remember now, did you run the engine OK before the rebuild - to rule out a split pick up?

Did you fit the oil pump gasket dry to minimise clearances?

Edited by 910Esprit

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I think tightened the olive pretty tight. Used wellseal on gasket. Run with good oil pressure before.

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Mmm, that's annoying. But would it make any difference? Seems reasonable that if the thermostat opened there would be zero oil pressure until the oil cooler and other pipes were full? I primed them but have no idea how long they would take to fill up as I took the thermostat off to check it. 

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Re-gasket.  I suppose it will be similar to having a couple of thou of axial wear, which doesn't sound much, but I always feel that a 907 has a very small oil pump for the number of bearings.   

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The pressure increase to 70 psi. If the pump was the problem how did it achieve the pressure? IMG_0101.thumb.JPG.77f26ea6b3161b5839e38e8c5b18612b.JPG

This  Is just before it cutout. When I restarted no oil pressure?

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Three possible reasons thermostat opened, air block or pressure relief valve. 

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The oil cooler is worthless until engine is hard at work for a period of time, in case you wish to cut that system out of the loop while sorting  out the rest.

Advisable to have preloaded oil into the cooler and lines. Concur on the value of care in assembling the pump,though can't add to discussion regarding use of sealant. The side clearance of rotors in the housing is critical to its efficiency, I can confirm. That said I advise leaving that for now unless you feel there may have been a considerable layer built up. It seems likely the pressure would plummet if lines were suddenly free to fill.

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Thanks we looked into that today. Basically the oil flow and return are just a loop until the thermostat opens. We checked the flow. Because the oil cooler pipes were not full maybe the thermostat opened and all the oil pressure was being used to fill the cooler?

Will try again tomorrow..

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I had a nightmare with initial oil pressure on my HC engine after rebuilding the oil pump. The only way to get oil pressure was to back prime the pump via the gauge sender port (mines a non Turbo) using a 12v oil pump. 

After some perseverance with the pump I managed to refill the oil lines and the pump sufficiently that spinning the engine over with the plugs out would pump oil back out of the sender port. Once I had that I started the engine and oil pressure was there within a few seconds. Been fine ever since, it's just that first 'dry' startup.

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Not worth starting anything now...🍺

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Yup - absolutely correct @eeyoreish - had the same with my S4s. I’m pretty sure it’s in the workshop manual about priming the oil pump. It was a pig on mine - it’s absolutely critical you get it right

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Only here once

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8 hours ago, 910Esprit said:

tsk tsk - That gasket should be fitted dry!

Actually thinking about it the Auxillery housing gasket has wellseal. The oil pump gasket is dry and was fitted by PNM who checked and rebuilt the pump.

The olive on the pickup was soaked in hot water, under Petes advice, then fitted. The pipe was seated at the correct height and the hex nut tightened twice. Once when hit then again after cold.

if there's a leak at the  pipe Incant see how it would acheive 75psi?

So why did the pressure drop after I restarted?

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Dunno - but you need to make sure oil pressure is being generated - don’t start it again !! Pull the spark plugs out and get a manual gauge of the oil line somewhere and turn the engine over in the starter. You must make sure you have oil pressure - otherwise you will do 10s of thousands of miles of damage to the engine in seconds

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Only here once

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2 hours ago, Lotusfab said:

Actually thinking about it the Auxillery housing gasket has wellseal. The oil pump gasket is dry and was fitted by PNM who checked and rebuilt the pump.

Well that's good news, Pete will have done it to spec. 

The point I'm making is that anything that effects the efficiency of the pump is undesireable - even a clapped out engine can deliver great oil pressure cold!   However, we can now rule that out for your engine.

I agree with Barry....   Maybe consider removing the oil cooler adaptor plate until you are confident all is as should be with the engine.   That will take all the oil cooler parephenalia out of circuit until you have got good consistent hot oil pressure. 

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Thanks chaps. We took the thermostat off to check it was installed correctly. When I precharged the cooler pipes I filled it from the engine out pipe. Thinking about it all this will do is fill the two engine pipes, as the thermostat will be closed. I need to take the pipe off on the other side of the thermostat then pump oil in. When it registers on the pressure gauge or comes out of the Turbo pipe drain the engine oil to the correct level then restart. Will report back how it goes.

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It might be good to try what we wanted to do but couldn't which was to fit the oil filter without the oil cooler sandwich plate, thus removing all the oil cooler plumbing.

For the record the way the cooler is plumbed is a standard aftermarket setup which uses a M-F extender to extend the filter screw on mount through the sandwich plate but this would not unscrew. Maybe the factory threadlocked it on to avoid it coming off when the filter is unscrewed.

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Isn't that an electrical guage? If so, after showing a good pressure initially & now nothing after the restart it sounds like a connection has come off. ☺

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Cheers,

John W

http://jonwatkins.co.uk

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I thought all G cars used the horrible plastic pipe to the gauge !  Hence the guage is mechanical not electrical ?  or did you fit a later type electrical guage and sensor Fabian to delete the plastic pipe risk  ?


A

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Just had another go. No oil pressure despite pumping oil through the Turbo feed. The oil level had gone down so I think the cooler had filled. I'm starting to think it's the pressure relief valve stuck open in the pump and it closed yesterday. I will have to take it off and check it for dirt. Only the distributor and five bolts.

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36 minutes ago, silverfrost said:

I thought all G cars used the horrible plastic pipe to the gauge !  Hence the guage is mechanical not electrical ?  or did you fit a later type electrical guage and sensor Fabian to delete the plastic pipe risk  ?

The pipe doesn't go all the way to the gauge, but to a transducer in the engine bay, and then electrically to the gauge.

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Likewise my S3 n/a has oil pipe into the guage.

ask me how I know...go on, just ask 😉

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