Aftermarket dipstick tube leaks

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like_A_pike

like_A_pike

that's not factory
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I have a 1971 340 in my 1968 Barracuda. It’s had a chrome dipstick since I bought the motor or it was on the 1976 360 that was in the car previously and I cannibalized it, I don’t remember.

I can clean the block and tube really well, use the black RTV, and can get 5000 miles out of it. Then it starts leaking again. I think that checking it is what loosens it but there may be a relationship between short spells of above average engine temperatures and failures too.

Anyway. It’s that time again and I’d like to see if there’s something else I could do to improve my process and results. O rings? OEM parts? Tap threads? What do you do?

Thanks in advance!
 
Are you sure its the tube or is the dip stick popping out do to crank case pressure?
 
dano said:
Are you sure its the tube or is the dip stick popping out do to crank case pressure?
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Pretty sure it’s down low. I am able to stop it for long periods with the RTV and if it was squirting out the top I’d have a much bigger mess and maybe even smoke. No oil is getting blown around by the nearby fan at the top of the tube. Just moist down low and leaves a half dollar size puddle overnight.
 
Mancini sells a raw steel dipstick and tube. That is what I bought for my small block. I haven't installed it yet, so I can't say whether it will seal or not?
 
like_A_pike said:
I have a 1971 340 in my 1968 Barracuda. It’s had a chrome dipstick since I bought the motor or it was on the 1976 360 that was in the car previously and I cannibalized it, I don’t remember.

I can clean the block and tube really well, use the black RTV, and can get 5000 miles out of it. Then it starts leaking again. I think that checking it is what loosens it but there may be a relationship between short spells of above average engine temperatures and failures too.

Anyway. It’s that time again and I’d like to see if there’s something else I could do to improve my process and results. O rings? OEM parts? Tap threads? What do you do?

Thanks in advance!
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I often clean and "tin" the insertion end with solder, to stop a loose stock tube, never had a leaky tube.
Clean well, tin, then gently wipe excess off while solder is still molten.

SOP when changing out engines.

Good luck
 
I'm not sure to be honest Doug, I tapped mine for npt.
like_A_pike said:
I am pretty attracted to this idea. Would I have to hone the block a skosh to accept a gas line fitting?
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20250603_194420.jpg
 
I've used those chrome dipstick tubes.
They can work okay, BUT- the chrome plating makes the bottom of the tube too big for the hole in the block. SOP is to grind off the plating, being careful not to get into the base metal; then driving it in. If someone got a little carried away and ground off too much it'll be a sloppy fit and as you found out, RTV (of whatever color) will only stop the leaking for a given amount of time.
I really like Inertia's idea of tinning the end and reinstalling to stop the leak on an existing tube.
I also like that Summit (Edit- Oops, I meant Mancini!) has a raw steel tube now- if it's a quality piece that's sized correctly, then that eliminates all the hackery. Plus you can then paint them block color the way Ma Mopar intended.
 
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I've also discovered that some tubes will form a near invisible crack/split at the "collar" after several installs, (mine) - if tapped too aggressively.

I like to slide an appropriate ring wrench down the tube, then use a long screwdriver or extension to tap on the wrench, spreading the impact around the collar.
Open end wrench may be used when nec.

Cheers
 
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like_A_pike said:
I have a 1971 340 in my 1968 Barracuda. It’s had a chrome dipstick since I bought the motor or it was on the 1976 360 that was in the car previously and I cannibalized it, I don’t remember.

I can clean the block and tube really well, use the black RTV, and can get 5000 miles out of it. Then it starts leaking again. I think that checking it is what loosens it but there may be a relationship between short spells of above average engine temperatures and failures too.

Anyway. It’s that time again and I’d like to see if there’s something else I could do to improve my process and results. O rings? OEM parts? Tap threads? What do you do?

Thanks in advance!
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Fix the blow by issue. If you don’t have a PCV valve hooked up get one.

There shouldn’t be that much pressure in the crankcase.
 
if you can pull out the tube its too lose
and nothing sticks to chrome
if you can get it dry and clean rough up the plating maybe jb weld
 
Newbomb Turk said:
Fix the blow by issue. If you don’t have a PCV valve hooked up get one.

There shouldn’t be that much pressure in the crankcase.
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I guess I did say squirt. I run at about 60psi @ 2000rpms. I have it on oil thinners to keep from having a stroke but that darn 30 weight sneaks out where it can! Lol I’m only kinda kidding. I like 20w 50 to prevent leaking but then it runs 100psi when cold!? I traded a pair of clogged breathers for one new one and a pcv set up with a little oil catch can. I’ve never been quite sure if it’s working properly however.
 
I've had a chrome dipstick and tube in my 340 for I don't even know how long. Since 1990 I believe. It has never leaked. I have to think that if yours is leaking where it goes into the block, then it's not really fitting tightly into the block for whatever reason. In your case, I'd just replace the tube.

Edit: the fact that you apparently can easily pull the tube out and put it back in, and have done so several times, confirms to me that your tube is not fitting tightly in the block. You should not be able to do that. I've had several small blocks over the years, and I've always had to (lightly) tap the dipstick tube in with a hammer. And they don't just pull out by hand. If I ever removed one, I think I probably had to use a punch or something and tap it out from the bottom.

1749013867367.jpeg
 
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My tube actually wiggles when the RTV gives up so I think we know what has to happen first!
Thanks again all.
 
like_A_pike said:
I have a 1971 340 in my 1968 Barracuda. It’s had a chrome dipstick since I bought the motor or it was on the 1976 360 that was in the car previously and I cannibalized it, I don’t remember.

I can clean the block and tube really well, use the black RTV, and can get 5000 miles out of it. Then it starts leaking again. I think that checking it is what loosens it but there may be a relationship between short spells of above average engine temperatures and failures too.

Anyway. It’s that time again and I’d like to see if there’s something else I could do to improve my process and results. O rings? OEM parts? Tap threads? What do you do?

Thanks in advance!
Click to expand...
Pull the tube out and a hammer a screwdriver into it, if it's a flat head do it about three different angles... then taken RTV it and Hammer it back into the hole. If you really want to get into it you can try and steak the hole in the block LOL..

But a different sound how Frugal you are, you could just buy a new one for Mancini
 
Less philosophy than infliction that frugality. Im in a program to get rid of it. One broken part at a time!!!
 
nutz said:
if you can pull out the tube its too lose
and nothing sticks to chrome
if you can get it dry and clean rough up the plating maybe jb weld
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I never had any luck with chrome items that contact any fluid under pressor, including water necks. As you say, sand to Ruffin up the chrome first. I personally would go to a junk yard and get a stock one.
 
I have to disagree with the statement that nothing sticks to chrome. Problem is that today too many of the chrome parts are junk.

I have chrome thermostat housings on my 67 Barracuda and 67 Hemi Charger. They've been on those two cars for over 30 years and have never leaked. The one on the Barracuda has been on four different intake manifolds and has never leaked on any of them.

I also have chrome dipstick tubes on my 65 Barracuda and the Charger, neither of which has never leaked in the 30+ years they've been on the cars.

I had to replace two more recent chrome thermostat housings, though. Couldn't get either one to stop leaking no matter what I tried. So I replaced one with a cast iron stocker, the other with a thick machined aluminum aftermarket one. I won't ever buy a new chrome thermostat housing again, nor a chrome dipstick tube either.

There are other things that used to be good, but are not today. I'm old enough to remember them, but I'm one of the fewer and fewer.
 
Yea i guess it's the crappy chome I have delt with oil pans and valve covers ..
Always seemed to leak
 
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