The Tragic Story of the Boy and His RB30

[Radical_Goodspeed]

As the title suggest this is not a happy story. A little back story for those who find the "why/how" interesting [If not feel free to skip down a paragraph or two].

Back in end of 2021 after saving all my birthday money, sell one RB26 project engine, and even parting way with one of my project cars I decided to take a huge leap in my GTR journey and purchased a complete RB30 bottom end from RIPS Racing. After months of waiting, the day finally came when the engine arrived at my shop. Understandable I was like a kid on Christmas morning wait with the shop doors open as the truck carrying my present backed in and delivered my engine. Only to have all my joy turn to dread as I noticed some damage to the packaging. Upon further investigation it turned out that at some point in its trip across the US something large and heavy crashed down on the the block cracking the rear drivers side oil return.

Wait you might say shouldn't insurance cover that? You did get the additional insurance didn't you? Welp....no...no I did not. This was my first time handling an international shipment that required additional insurance and I learned the hard way what "limited liability" means and because I didn't get said insurance I was stuck trying to figure out what to do next.

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So after assessing the damage and getting the sad new from the shipping company I reached out to RIPS to see what could be done to make the block useable. [See below response from RIPS]

I’d put a straight edge on the deck surface and see how much the outer edge had dropped and then make the call of either cleaning the inside and the outside of the block and smear some high quality high temp 2 pack epoxy over the crack inside and out not allowing any to protrude above the deck surface (could literally wipe it off the deck surface while its wet) then once fully cured and all the rags out etc when installing the head gasket and head, apply a tiny amount of high temp sealer to both sides of the gasket in that area, torque the head up as usual, install the little M6 bolt with a spring washer only (this ill dig into the head and allow you to nip up the bolt GENTLY and it won’t come loose. If you go too tight you would risk braking that little area of the head casting so it wouldn’t need to be very tight at all, just enough so the M6 won’t come loose.

 Alternatively If the area has dropped too much you could carefully break that small section off, clean up any burrs remove some material in a V on the inside and outside edges of the crack (on the removed section only and possibly the OUTSIDE of the block, not in the inside) then test fit it until you can see its sitting back exactly where it was, the top is flush and level (it will naturally kind of click back into place) then clean everything real good and do the same as above with the 2 pack epoxy and gently clamp across the block (with a woodworking clamp with soft pads) make sure nothing is proud on the deck surface then once fully cured, as above apply just a tiny amount of sealer both sides of the gasket just in that area and once again just nip up the M6 bolt enough so it won’t come loose.

I reached out to a local machinist, mans built/worked on everything from nitrometh bikes to COBBs R35, and he recommended something similar. His only additional concern was supporting the cracked area and ensuring that the damaged position doesn't "pop" off. Unfortunately do to the location of the crack there's no good way to run a bolt from the outside of the block into the water jacket to lock it in place. I've looked into "block sticking" and most traditional methods are likely to make the crack worse as it pushes they the metal apart as the bolt and tap go in. I have looked into Lock-N-Stitch which is specifically designed to pull material in as its installed but I'm not sure if that would work or be applicable in this circumstance given the location of the cracks and the fact that at least to some degree the crack goes from one side to the other. The only other thought that's been bouncing around in my head is running the epoxy on the outside completely across from one crack to the other to create a skin/outer layer to try and mitigate the chances of the damaged section popping off. I've attached the pictures of the damaged area as it currently sites.

Any advise you guys can give would be greatly appreciated and my apologies for the lengthy post but this has been a very long a draining process. 

[TurboTapin]

Although they do seem to work, I personally would never trust epoxies on a block. I would constantly be concerned every drive is my last.

Although cast iron is a pain in the rear to weld, it's very doable and this small part looks like a perfect candidate. I would also put more faith in brazing it vs a 2 part epoxy as well which will still require a lot of pre heat and post slow cool but would be easier to do. 

Edited January 25 by TurboTapin

[Looney_Head]

mate that sucks

Not having done anything like that before I would follow RIPS second option as you will get better coverage of the eproxy. once the head is on it will support it so it won't pop off.

[GTSBoy]

Any of the approaches described could work, and any of them could fail after sometime/distance.

Looking at the photos, I would say that RIPS recommendations are possibly valid provided the top surface hasn't dropped, as they say. But I look at the widest gap on that crack and I think to myself.....that's not going to stay there.

If trying to salvage it with epoxy approaches, I would do one of two things. I suspect that the first thing might even be a fallback position if the 2nd thing doesn't work (ie if the second style of repair resulted in a failure where the patch falls off).

1. Drill the bottom ends of the cracks to attempt to stop them propagating (we're talking very small drill here). Drill holes through from the wobbly bit into the good walls of the block. Diameter suitable to take a good sized cap screw. Cut a step in around the outer end of the hole to provide a shoulder for a cap screw to sit on and apply force to. Clearance drill the part of the hole in the wobbly bit to clear the thread of the cap screw. Tap the holes in the block wall. This so that you're not engaging thread in the wobbly bit. You're only trying to push the wobbly bit back towards where it came from. Apply sealant to the crack area as RIPS suggest and then put in the bolts and pull the cracks closed.

This part of the block is very non-structural and there are no significant loads there, but I would very much worry about that bit deciding to jump off the rest of the block if there is not some sort of mechanical connection providing for in the right direction to prevent the crack propagating further (which would likely propagate around to complete the loop and make the wobbly bit come off.)

2. Bite the bullet and rip the wobbly bit off. Drill 2 or 4 holes into the block wall on the exposed fracture surface. Tap the holes and pop in some cap screws to act as anchors. Break out the Devcon and pretend you're back in pre-school and remake the broken off section. Prep the top surface and put in the M6 hole (perhaps put in a helicoil there, and....cross fingers.

I have seen a Peugot 504 engine have substantial parts of the block face and the front end of the head remade in Devcon and last for years and years. You can perform miracles with the stuff if you work clean and smart.

 

Anything that just fills the crack with sealant is likely to leave the M6 hole out of alignment with the head. If you can get the head on and test fit that bolt, you might be able to allay the fear of that happening.

 

Otherwise, per Andrew's suggestion, I would definitely take it to someone who is confident and experienced at welding cast iron, particularly blocks and heads. Because again, as this area is not structural, you only need it to keep the oil on the inside and not just drop off and wave around in the wind.

Edited January 25 by GTSBoy

[Radical_Goodspeed]

Thank you all so much for your advise and suggestions 😊.

 @GTSBoy I think I'm going to go with your first option. I attached a few photos with my first stab at where to put the bolts to brace the wobbly bit and would love your feedback and thoughts. On the back I outline two spots for bolts one low one high. The lower one I think will be easy to set up but likely wouldn't draw the crack closed much. The high one would definitely close the gap but would be a challenge to drill properly. Do you think it's worth doing both or just going with the lower option?

The only other major challenge I see is try to drill these out but I think I can pull it off with a radial drill press by coming at it from the side.

[GTSBoy]

Hmm. Just the top ones I think. I think you need to drill the tail end of teh crack (if you can find it properly) to stop it propagating, and that might be difficult to do if you also try to put another cross bolt into the lower end of the long crack. The worst part of the problem is that on the inside it looks like the crack has run all the way down and around. Meaning that it already wants to jump off.

Good luck with the drilling. Some sort of jig/fixture is definitely going to be needed to make sure that everything stays trued up while you do it. I'd also hate to do it by hand/eye.

[Radical_Goodspeed]

I figured give the crack seems to have propagate from one side to the other, at least on the inside, the lower one would serve as a good anchor to keep it from jumping off while I work the rest of the bolts. 

[GTSBoy]

Maybe. Make your decision as you go, perhaps.