Dartgame Posted May 25, 2017 Report Share Posted May 25, 2017 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... Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted May 25, 2017 Report Share Posted May 25, 2017 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... 1 Quote Link to comment Share on other sites More sharing options...
dpollo Posted May 26, 2017 Report Share Posted May 26, 2017 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 . Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted May 26, 2017 Report Share Posted May 26, 2017 A 1/4" pipe tap seems to want to thread into the valve.... Quote Link to comment Share on other sites More sharing options...
Dartgame Posted May 26, 2017 Author Report Share Posted May 26, 2017 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. Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted May 26, 2017 Report Share Posted May 26, 2017 study of one of the pistons...with the very heavy base on the forward edge..not thinking collapse as an alternative... Quote Link to comment Share on other sites More sharing options...
Dartgame Posted May 26, 2017 Author Report Share Posted May 26, 2017 Good thought- need to examine a piston outside the block. Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted May 26, 2017 Report Share Posted May 26, 2017 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. Quote Link to comment Share on other sites More sharing options...
Flatie46 Posted May 26, 2017 Report Share Posted May 26, 2017 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. Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted May 26, 2017 Report Share Posted May 26, 2017 Pictured below is what the oil pressure piston looks like in my Desoto engine. Yours may be different. Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted May 26, 2017 Report Share Posted May 26, 2017 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. 1 Quote Link to comment Share on other sites More sharing options...
JBNeal Posted May 26, 2017 Report Share Posted May 26, 2017 would this scenario be a candidate for the candle wax method? 2 Quote Link to comment Share on other sites More sharing options...
Dartgame Posted May 26, 2017 Author Report Share Posted May 26, 2017 Great ideas guys. Need to get the block out of my machinists shop where it has been siting for a while. Will probably do this next week. He is probably closed tomorrow... Quote Link to comment Share on other sites More sharing options...
classiccarjack Posted May 29, 2017 Report Share Posted May 29, 2017 Please let us know how it turns out. Quote Link to comment Share on other sites More sharing options...
40plyguy Posted June 10, 2017 Report Share Posted June 10, 2017 Wondering if you got the relief valve piston out and what method you used. Having the same issue............. Quote Link to comment Share on other sites More sharing options...
40plyguy Posted June 14, 2017 Report Share Posted June 14, 2017 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! Quote Link to comment Share on other sites More sharing options...
Flatie46 Posted June 14, 2017 Report Share Posted June 14, 2017 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. Quote Link to comment Share on other sites More sharing options...
dpollo Posted June 14, 2017 Report Share Posted June 14, 2017 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.. Quote Link to comment Share on other sites More sharing options...
Dartgame Posted June 14, 2017 Author Report Share Posted June 14, 2017 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. Quote Link to comment Share on other sites More sharing options...
dpollo Posted June 15, 2017 Report Share Posted June 15, 2017 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 ! Quote Link to comment Share on other sites More sharing options...
40plyguy Posted June 15, 2017 Report Share Posted June 15, 2017 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........................ Quote Link to comment Share on other sites More sharing options...
Dartgame Posted June 15, 2017 Author Report Share Posted June 15, 2017 Thanks for the thoughts. The block can wait, no rush- just being cautious, don't need to reverse the recuperation progress. 1 Quote Link to comment Share on other sites More sharing options...
Dartgame Posted October 31, 2023 Author Report Share Posted October 31, 2023 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. 3 Quote Link to comment Share on other sites More sharing options...
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