Saturday, June 27, 2015

Oil Pressure Relief Valve

<This post is part of the 'New Engine Rebuild' project>
In the interests of being thorough with the engine build, I thought it best to make sure the oil pressure relief valve was checked over to make sure it was okay. Plus I haven't a clue what lives behind that large nut, so this is an ideal opportunity to find out!

Finding a 1" socket, I undid the nut and gave it a few turns. According to the Haynes manual, it looked be spring loaded so I wasn't quite sure what to expect. Worst case scenario is that the nut would be catapulted across the room, as I didn't want to take any chances I thought I'd better 'plan for the worst and hope for the best.

Undoing the nut very slowly and carefully I braced myself as it left the last of the threads and... nothing, no dramatic 'P'Doing' or anything. To be honest it was pretty easy to push against the spring with little effort once it was off. Good in one respect, but a bit boring in another.

Removing the nut completely, it left the protruding spring very easy to remove.

The inner bullet looking 'cup' part of the assembly was a little more difficult to extract though as it was buried way down in the narrow hole. Thankfully, it was not corroded and didn't need any special tools or persuasion to tease it free, in fact I found that the end of the spring was enough to fish it out.

Once it was out, I could examine it properly. Although it looked in good condition apart from a few scratches, I decided to renew it anyway as they are very cheap to replace. When I was at Mini Spares North discussing the situation, I was planning to change the cup for a ball bearing as the were advertised as being better, however the word of those in the know, is that the tried and tested cup was still the best. So I heeded the advice and went for the cup.

Next thing to check was the length of the spring. The specs for this are in the Haynes manual so I looked them up and found that the uncompressed spring should be 72.63mm long. Placing it against a ruler, it seemed to measure up pretty well so I decided to reuse it.

The last thing to consider was the nut. It's quite a chunky thing and nearly £5 to replace, which seems a bit steep for a nut. Looking at the one I had though, I decided all it needed was a freshen up with a wire brush and it would by fine.

Putting the parts back in is as easy as it sounds... Put the cup in first, then the spring then the nut, the only slightly tricky part is pushing the nut to compress the spring while trying to get it to catch the thread. Once it has caught the thread though, the socket could be used and it was soon torqued back into place. 59Nm if you were wondering!

Okay, this was a fairly easy little side 'project' if I can use that word, but as the oil pressure relief valve it quite an important little component, I wanted the reassurance that it was done and done properly. Plus it offered the chance to learn a bit more about the specifics of the engine, and that is a massive part of why building the engine, so all my boxes are ticked now :)

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