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Oil pressure relief valve ?


Dartgame

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Hi All - I am working on a salvage '53 218. Person that gave me the block had it hot tanked, which is nice, but they did not remove the pressure relief valve assembly. I was able to remove the cap/plug and the spring, but the pressure relief piston is firmly stuck/rusted into the block. Have tried heating soaking with oil, and using a huge easy out..No good. In speaking with my favorite machinist about this he is suggesting drilling it it out. In order to do this he would like to see what the piston looks like. Which brings me to my question.

Does anyone have a used pressure relief valve assembly they would be willing to sell me ? Or a piston from one of these ? I know I can buy a new one from VPW, but am trying to avoid as much expense as possible should this block end up being junk...

Thoughts & comments appreciated...

 

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your odds of drilling out the valve and not mess up the "bore" that it slide into is going to be slim and not damage the block beyond use ...look inside and you can see that there is a hole in the back of the valve....you can try to thread this if you wish but I think it is a pretty hardened so I suggest to use a very good grade metal screw and thread it into the hole....they I would do my best to relieve any rust that is binding it due to improper prep for the hot tank...I would try heating it with a good torch......let it cool..heat it again...let it cool a bit then with the screw in place use a slide hammer to shock it..do not slam it..shock it a bit...then a bit more..check that the screw is still in the piston good and continue the shocks and alternate with heat till it comes loose...

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Good advice from PA.   If you can somehow get air pressure behind the valve, it may move but put the cap in place (without the spring) or it could come out like a bullet !    You would have to install the crankshaft and camshaft to block all the oil holes.  not easy especially since the cam bearings probably got eaten up by the hot tank process and you do not want to waste a new set .

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A 1/4" pipe tap seems to want to thread into the valve....

IMG_3531.JPG

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Thanks - I'll give the 1/4 tap a Shot - problem with heating is I'd need a acetylene torch to get enough heat - which I do not have. Machinist was suggesting a slightly smaller drill to weaken the piston thereby allowing to collapse. Good idea about threading into the piston as well, but with as hard as this thing is may be an issue as well. But we will see what works. 

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You can waste out the tap if you need just to be able to do what you need to free up the piston.Twist on it try to turn it etc.

if you were good with a stick welder or even mig you could loosen it that way too.

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If a 1/4 tap threads into the piston you could take 1/4 X 3" or 4" long nipple and weld a washer or something to the end to attach your slide hammer to. Then screw it in and slap it like it owes you money. You need to heat the area around it though. Preferably with an acetylene torch. Acetylene burns about 500degrees hotter than propane. It will get the area around the piston hotter faster therefore allowing the hole to expand and let go of the piston.  Remember heat around the piston and try not to heat the piston as much as possible, If it were me, I would heat it and get it really hot then let it cool completely a few times. Heat cycles will help separate it. When you attempt to slap it out start from stone cold  though that way the piston starts out as cool as possible( and small ) in your race to get the surrounding area hot and expanded. Good luck.

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The area around the piston is not easily heated as the piston is deep into the block but anything is worth a go.

Ballistol  lube and getting a good grip on the piston should get it out..

I have removed several with the tap or threaded bolt method.

I'd like to see the rusty block and piston.

Oiling System Ply Dodge Flahead (6).JPG

Oiling System Ply Dodge Flahead (2).JPG

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  • 2 weeks later...

Got the relief valve piston out today. Used a cheap (Harbor Freight) 1/4 pipe tap. It easily threaded into the valve. As I was threading it in the piston started turning. Worked it back and forth a bit and out it came.  It was stuck because of sludge not rust. Glad it's out. One more time in the hot tank and it's off to the machine shop!

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Glad to hear ya got it out. Some day another Mopar guy will be going through the same troubles and you can  pass along what you did to resolve the issue.

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Over thirty years ago I assembled an engine for someone who had all the machine work done already.  On final assembly I noticed the relief valve was stuck in place and had been there all through the cleaning and machining .  As I was not being paid for this work I found the quick fix was to install the  oil pump  from a 53 Chrysler which had the  oil pressure relief valve in  the cover.   It worked just fine but the oil filter had to be hooked up differently.   It is still running and I am certain the plunger is still stuck.

Glad persistance paid off for you.   I never did collect money or favors for this job but can chalk it up to experience..

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I have not gotten the block out of the shop. Screwed up my left arm (badly pulled and bruised muscles) helping a friend replumb his house. No heavy lifting for a while, and certainly a flat head block qualifies as heavy. Maybe early next month. Meanwhile I sent the 52 off to the paint shop for some surgery on a very old collision repair...curious to see how it comes out.

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Good luck with your repairs, automotive and personal.   I remember when a Plymouth block wasn't so heavy,  I have hay to bring in next week and even the 50 lb "grampa bales" are heavy now !   Average age of the hay crew....... 70 !

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dpollo, don't feel so bad, no one's getting any younger. Today's my birthday and I can attest to that......................Anyway, I'm glad the relief valve issue was posted. I thought I had my 230 block completely stripped down. Hot tanked it twice.. Read the posting and got curious. Sure enough the relief valve piston was still stuck in the block............Glad this website exists........................

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  • 6 years later...

Reviving an old thread - I finally got the Oil pressure relief piston out of the block.

 

For those interested - the piston itself is not made of really hard steel. I found it could be drilled, in a quite normal fashion.

 

So, I tapped it for 1/4 - 20 and bought a grade 8 bolt. Heated cooled whacked it, oiled it etc., while tightening/pulling against the block with heavy washers, and finally snapped the bolt off in the piston without any joy. Fiddled around with a dremel and got the broken piece to spin out, Yeah ! Drilled the piston using an F drill bit and tapped for 5/16 coarse thread. Used a grade 8 bolt and heavy washers to pull against block casting, similar to last failed attempt. Heated cooled whacked it and finally creak !? checked the bolt, - nope its fine, heat whack, oil, tightened, creaked, and then creaked again and again, Voila ! It came out. Boy was the thing screwed, crudded heavily with gunky rusty crap.

 

So why did I go after this thing 6 years later ? Well, that's another story. 

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