421 cub leakdown test.....uhh ohh!

[CAJUN BANSHEE]

Finally have some time off to finish my build so decided to build a leakdown tester today. Man I would have been screwed if I didnt. It wouldnt hold 6psi for 2 seconds. I could hear the air escaping from the bottom of the right hand cylinder. Pulled her apart to check my gasket and this is what I found...

 

Its two very small indentions on the case where the cylinders mate. Would it be a good idea to put a thin layer of rtv over the slightly damaged area? Or am I sol and need to search for some new cases.

[CAJUN BANSHEE]

 

Heres a better pick. You can see the two parallel dents on the outside edge close to the front stud.

[LilJockey481]

yamaband it I do just as a precation plus it will def help seal it up

[RadarRacing]

Yamabond and retest it after reassembly. I wouldnt sweat it at all if it holds ok.

[CAJUN BANSHEE]

Thanks yall, thats what Ill do. Sure glad I did a leakdown test because that would have been a mechanical, physical, and mental meltdown.

[mike0chek]

i 3 bond everywhere on the motor where 2 surfaces meet and it never leaks on those area's. put some sealant there and you should be fine.

[CAJUN BANSHEE]

i 3 bond everywhere on the motor where 2 surfaces meet and it never leaks on those area's. put some sealant there and you should be fine.

Well Mike, wish I would have read this earlier, now that I have fixed that one area another has popped up. But its my own hardheadedness because I didnt finish checking the rest of the motor for other leaks. Now I ordered another gskt and more sealant with No Limit and I will pick up on this again next weekend. uuhhhggg Thanks again for the info fellas and ride for me this weekend!

[mike0chek]

Well Mike, wish I would have read this earlier, now that I have fixed that one area another has popped up. But its my own hardheadedness because I didnt finish checking the rest of the motor for other leaks. Now I ordered another gskt and more sealant with No Limit and I will pick up on this again next weekend. uuhhhggg Thanks again for the info fellas and ride for me this weekend!

 

i was fortunate enough to hear those words from kevin himself (apply sealant to places where 2 surfaces meet) that includes your reed gaskets and all. it was totally worth it because i had no leaks after. dont worry, when you see that gauge hold 6 lb's you will be very confident in runnin that motor

[CAJUN BANSHEE]

i was fortunate enough to hear those words from kevin himself (apply sealant to places where 2 surfaces meet) that includes your reed gaskets and all. it was totally worth it because i had no leaks after. dont worry, when you see that gauge hold 6 lb's you will be very confident in runnin that motor

Right on bro, Im on the right track now. Now if I can keep my home made tester from leaking lol Ill build a better one tomorrow.

[dirtydownunder]

i spray my base gaskets with hylomar spray.

 

throw a straight edge on it, and see if its bowed at all.

[CAJUN BANSHEE]

i spray my base gaskets with hylomar spray.

 

throw a straight edge on it, and see if its bowed at all.

Whats hylomar spray? But I did put a straight edge on the base and never found the damage until I felt with my finger. Even put a flashlight behind the staight edge.

[dirtydownunder]

just a gasket sealing compound spray. you can get it in a tube or a spray can. i use the spray.

[okbeast]

[mike0chek]

that stuff will def work but i can say from personal experience that yamabond or 3 bond will seal anything lol so if you have some extra from doing your cases use it!

[CAJUN BANSHEE]

 

Oh yeah, I've seen that. Might be a lil messy though.