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Under Pressure. 
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Part built GTM

Joined: Tue Apr 14, 2015 6:56 pm
Posts: 51
Post Under Pressure.
Well hi back with more progress. Despite recent lock down and isolation progress on the coupe has been slow, partly due to other commitments and partly due to me doing things more than once. For example fitted a mildly tuned 998cc engine then found a 1275 mg metro engine and installed that instead. Other issues have been more frustrating, like the standard master cylinders not fitting under bonnet and even with bango connections have only 4 mm clearance. The main cause of my reverse progress has been the wiring loom that a bought new from the company mentioned in this club. After waiting 12 weeks for it the item arrived without and labeled wires and no wiring diagram, this has proved to be a complete ball ache to put it mildly. Despite some of the wire not being connected correctly and required removing and in some cases rewiring everything is now working electrical as it should. Car is now wired plumbed and full of liquids, with any luck it may be ready for next classic Le Mans.
Now for the latest issue, I gave the M.G. Metro a basic overhaul before installing it, good clean, new oil pump, water pump, timing chain and sprockets, oil relief valve, clutch, oil seals and decoke and installed. Spent last night cranking it over with no plugs to get oil pressure, oil warning light went out gauge registered nothing after half an hour. Bugger! Tonight swopped gauge, light went out within seconds needle on gauge shot off round the dial slowing at 90 and stopped at 100psi!!!! Could this be a faulty gauge or is there really that much pressure? Took oil pipe off back of gauge, cranked over and thick black oil dribbled out. So what is wrong, could the new uprated pressure relief valve ( ball bearing type) be sticking or could some oil ways be blocked in the block? The starter motor doesn't seem slow down even with this pressure.
Is it wise to try and run engine?? Please could someone advise me????


Fri Oct 02, 2020 7:36 pm
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Joined: Wed Jul 31, 2013 11:47 am
Posts: 911
Location: Kano north Nigeria
GTM: Cox/Coupe
Post Re: Under Pressure.
I have always cleaned out the long oil passage along the length of the block, if that were blocked no oil feed to mains, etc and could lead to very high pressure, but the ball type (or cone) relief valve should lift to let excess pressure out.
I know its a butt ache but best checked, especially if the engine history is not known.
I have lost count how many times mine has been removed to trace/cure a fault in the last year!!!
John


Sat Oct 03, 2020 6:49 am
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Part built GTM

Joined: Tue Apr 14, 2015 6:56 pm
Posts: 51
Post Re: Under Pressure.
Have just removed uprated from MG engine and standard one from 998 engine. Apart from obvious diffence in shape the uprated one appears longer, does this account for pressure diffence? Will fit and try it later later . Tried posting photo but it is invaled.


Sat Oct 03, 2020 9:07 am
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Joined: Fri Sep 28, 2007 7:39 pm
Posts: 564
Location: Aberdeenshire
GTM: Cox/Coupe
Post Re: Under Pressure.
There were shorter springs available to go with the ball bearing, rather than the "bullet" type ones.
Maybe someone has replaced the spring for one they had lying around when they put in the ball.

90 PSi range with cold oil would be a good sign, 100+ could just be the gauge.

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Sat Oct 03, 2020 3:37 pm
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Part built GTM

Joined: Tue Apr 14, 2015 6:56 pm
Posts: 51
Post Re: Under Pressure.
Thanks Ken. Just cranked her over with standard valve and have got 72psi cold which sounds ok to me. Next will be to fire her up. I think many up rated items are not really suitable for mild or even fast road use.


Sat Oct 03, 2020 10:24 pm
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