MGB The easy way to get the oil pressure relief cap nut back on

[max71]

I've been dealing with low OP and trying experiments on changing springs, packing, etc. Everyone I talked to who did this job said its hours of work and one of the most miserable jobs with the engine in the car. After having a special tool made and trial and error I got it down to ~ 20 minutes and pretty painless. I once took the car to a mechanic who spent almost 2 hours trying to get it in using a lift.

Here's the recipe:

1. Get some kind of spreader. I bought a tool that was used to remove C clips and had a couple parts welded on. Photos attached.
2. Known tip: Play with the cap nut to find where it starts to thread in and mark that place.
3. Although the tool I made was meant to be used just with the cap nut directly the problem arose when trying to turn the nut due to very limited space. So using a tip from Peter Burgess, I cut down a 1" socket. You cannot get the socket wrench in there until the nut is pretty far down. So I put put a lock tie on the socket with the nub positioned to where I could get to it with the socket positioned where the threads start on the cap nut/block. (see above) and mark the socket to correspond.
4. With everything in place (also a bolt at the bottom of the socket so it can be held by the spreader) you just begin to use the spreader worm screw until it mates up with the threaded hole. Not difficult but may take a couple practice runs to make sure its straight in
5. Use whatever you can to then spin the socket/cap screw using the nub from the lock tie. One full half turn does it.
6. Unscrew the spreader and turn the socket by hand until its pretty close to the block
7. Take you socket wrench and finish the job.

Really easy. If you require more photo's let me know. BTW, make sure to use a copper washer or copper crush washer. The fiber washer that many parts houses sell leaks.

 

[DrEntropy]

This task seems sooo easy from the innocuous look of that cap nut from the outside. It's only when you try compressing that spring for the first time with the engine in situ, you find you've opened a can of worms!

First time we did this was back in the late sixties. Took a couple hours of MacGyverin' different levers, tool "repurposing" and general thrutchin' about accompanied by colorful language before it finally caught the threads.

Congrats, Max! Well done.

 

[davelinkson]

Refitting oil pressure relief valve cap

A tip on refitting the cap to 4-cylinder cars more than anything else.
Bearing down against spring pressure whilst trying to get the threads engaged is one of those 'worst jobs' on the MGB. Refit the cap without the spring, slowly unscrew it, and mark the cap and block where the threads just disengage. Now you can refit the spring and position the cap just before the threads will engage and not only will you know where the threads will engage, but also that whilst fighting the spring you will only have to turn the cap a few degrees to do it.

 

[PAUL161]

Max, thanks for that bit of info! Any way this job can be made a little easier is very welcome. Good job! PJ

 

[max71]

Dave - did you read my post? That is the second thing I mention.

 

[max71]

Thanks Paul!

 

[Simmo]

I've been dealing with low OP and trying experiments on changing springs, packing, etc. Everyone I talked to who did this job said its hours of work and one of the most miserable jobs with the engine in the car. After having a special tool made and trial and error I got it down to ~ 20 minutes and pretty painless. I once took the car to a mechanic who spent almost 2 hours trying to get it in using a lift.

Here's the recipe:

1. Get some kind of spreader. I bought a tool that was used to remove C clips and had a couple parts welded on. Photos attached.
2. Known tip: Play with the cap nut to find where it starts to thread in and mark that place.
3. Although the tool I made was meant to be used just with the cap nut directly the problem arose when trying to turn the nut due to very limited space. So using a tip from Peter Burgess, I cut down a 1" socket. You cannot get the socket wrench in there until the nut is pretty far down. So I put put a lock tie on the socket with the nub positioned to where I could get to it with the socket positioned where the threads start on the cap nut/block. (see above) and mark the socket to correspond.
4. With everything in place (also a bolt at the bottom of the socket so it can be held by the spreader) you just begin to use the spreader worm screw until it mates up with the threaded hole. Not difficult but may take a couple practice runs to make sure its straight in
5. Use whatever you can to then spin the socket/cap screw using the nub from the lock tie. One full half turn does it.
6. Unscrew the spreader and turn the socket by hand until its pretty close to the block
7. Take you socket wrench and finish the job.

Really easy. If you require more photo's let me know. BTW, make sure to use a copper washer or copper crush washer. The fiber washer that many parts houses sell leaks.

 

[Simmo]

Hi Max, I am totally frustrated with installing this spring and nut. Your article seems to solve the problem but it still confuses my small brain. Could you please send me some more pics so hopefully I can understand your method. Cant seem to invisig the assembly with the Tool and Socket together. If you are using the socket for the final screw down and it doesnt assemble with the took, OK. Then show me how the tool worked with the nut and spring, that is with compression weight. My email is : secsimmo@bigpond.com
Regards
ian

 

[JPSmit]

Ian this is a thread from 2015 and Max has not been seen on the forum since 2016 - so hopefully some others will chime in. Good Luck!