XR2 Racer - block cracked!!! AAGGHHH!!
Discussion
The bad luck we have had with our racer has got worse! Now the block has got a crack in it. We have been told that this is virtually unheard of!
First time for everything...
anyway, the solutions we have heard are
1. total rebuild again, bedding in and rolling road etc.
or
2. Welding the block and clamping it (profesisonally done by bloke who does only this for a living!?)
what are peoples opinions on the clamping and welding, will it withstand race stresses, or is it a temp solution that wont last?
We have been told it will be good as new when its done and no need for rolling road etc. again, so means we can get out for brands hatch, and not miss another race
:-(
help, advice, opinions all welcome!
First time for everything...
anyway, the solutions we have heard are
1. total rebuild again, bedding in and rolling road etc.
or
2. Welding the block and clamping it (profesisonally done by bloke who does only this for a living!?)
what are peoples opinions on the clamping and welding, will it withstand race stresses, or is it a temp solution that wont last?
We have been told it will be good as new when its done and no need for rolling road etc. again, so means we can get out for brands hatch, and not miss another race
:-(
help, advice, opinions all welcome!
Dank
your having some serious bad luck with this motor !
Is the crack in anyway connected to the failed core plug it suffered?
in the past i've seen cracks in the block repaired.
most drill a hole at the end if the crack to stop it from expanding, then relieve the stress before welding and finishing it off.
i've never seen a CVH block crack through use, I have seen them go with rapid cooling or excessivley high coolant pressure though.
where abouts is the crack?
your having some serious bad luck with this motor !
Is the crack in anyway connected to the failed core plug it suffered?
in the past i've seen cracks in the block repaired.
most drill a hole at the end if the crack to stop it from expanding, then relieve the stress before welding and finishing it off.
i've never seen a CVH block crack through use, I have seen them go with rapid cooling or excessivley high coolant pressure though.
where abouts is the crack?
Hi Nighthawk, well we thought the slight water leak down the front of the engine block was the coreplug slightly leaking as i posted some time ago, infact it turned out to be a hairline crack i the block which has steadily increased over the duration of one big track day and 3 races. Its now stretching across the front of the block, i think about 3-4 inches across. I have taken some pics of it at
www.subscribeweb.co.uk/docs/block.jpg
There is no way it could have been caused by frost etc as we had plenty anti freeze in there from when it was built and also we wrapped the engine up in blankets and had a car cover over it on the drive. We have been advised it may have just been a hairline fracture in the bloack that was not spotted when rebuilt and that the stresses of the races have caused it to crack more!
Its very very annoying, we just seem to be having problem after problem with this!
www.subscribeweb.co.uk/docs/block.jpg
There is no way it could have been caused by frost etc as we had plenty anti freeze in there from when it was built and also we wrapped the engine up in blankets and had a car cover over it on the drive. We have been advised it may have just been a hairline fracture in the bloack that was not spotted when rebuilt and that the stresses of the races have caused it to crack more!
Its very very annoying, we just seem to be having problem after problem with this!
Hi m8
Looking at the larger of the pictures, it looks like the crack extends all the way to the raised bolt hole, so i'd not expect that to be as durable post repair. hope for your wallets sake it can be saved though.
If the engine has been built by a reputable builder the crack shouldn't have been missed.
I'f it was one I was going to build, the block would have been subjected to NDT before the build got underway.
fingers crossed everything goes well.
Looking at the larger of the pictures, it looks like the crack extends all the way to the raised bolt hole, so i'd not expect that to be as durable post repair. hope for your wallets sake it can be saved though.
If the engine has been built by a reputable builder the crack shouldn't have been missed.
I'f it was one I was going to build, the block would have been subjected to NDT before the build got underway.
fingers crossed everything goes well.
Hi mate
The engne was built by a reputable builder and he assures us that the block was thoroughly checked and all the rust stripped off before he painted the block and rebuilt the engine. What can we do!
Its a delicate and frustrating dilema and turning out to be bloody expensive!
What would you think we should do. We have heard reports from other non-race car based mechanics that pinning and welding is only really a temporary solution and not a long term one.
Would you think this would last race stresses then?
Would it do a season or two or will it all go bang well before then?
We're not expert enough in engineering or mechanics to argue against the pinning or welding.....there is the possibility that if the engine is welded etc. and then goes bang, we will take it back and ask for it to be rebuilt, taking alot of time and more money, but hopefully he will feel obliged enough to rebuild it minus labour costs and maybe parts!
I don't know what to do, the welder guy is booked for tuesday so iam trying to arm myself with some advice/opinions and facts so we can take the best course of action from this point. The next race is rapidly approaching and we need this fixed!
The engne was built by a reputable builder and he assures us that the block was thoroughly checked and all the rust stripped off before he painted the block and rebuilt the engine. What can we do!
Its a delicate and frustrating dilema and turning out to be bloody expensive!
What would you think we should do. We have heard reports from other non-race car based mechanics that pinning and welding is only really a temporary solution and not a long term one.
Would you think this would last race stresses then?
Would it do a season or two or will it all go bang well before then?
We're not expert enough in engineering or mechanics to argue against the pinning or welding.....there is the possibility that if the engine is welded etc. and then goes bang, we will take it back and ask for it to be rebuilt, taking alot of time and more money, but hopefully he will feel obliged enough to rebuild it minus labour costs and maybe parts!
I don't know what to do, the welder guy is booked for tuesday so iam trying to arm myself with some advice/opinions and facts so we can take the best course of action from this point. The next race is rapidly approaching and we need this fixed!
Only you can make the choice on this m8, if you go with the weld option it may well hold throughout the rest of the season, but it's never going to be a permanant solution to it.
On a normal car it could last out the life of the car,but your engine is going to be working hard.
That crack looks like it's travelling towards the altenator mounting bosses, this is an area under different stresses, worst case would be losing that entire area on the track and dumping the coolant before demolishing the rest of the block and wiping out the rods and crank, so something needs to be done quickly.
I don't think you'll get a G/T off the welder as to it's longevity, If it were mine, i'd have it welded while a replacement was being prepared.
If all the rust was cleared and the block NDT'd without issue, then something has caused that to happen because it's not a common one.
I'd like to see a few other pictures of it, maybe the fracture has come from an overtightened bolt either through the head or the water pump housing.
good luck with it m8.
On a normal car it could last out the life of the car,but your engine is going to be working hard.
That crack looks like it's travelling towards the altenator mounting bosses, this is an area under different stresses, worst case would be losing that entire area on the track and dumping the coolant before demolishing the rest of the block and wiping out the rods and crank, so something needs to be done quickly.
I don't think you'll get a G/T off the welder as to it's longevity, If it were mine, i'd have it welded while a replacement was being prepared.
If all the rust was cleared and the block NDT'd without issue, then something has caused that to happen because it's not a common one.
I'd like to see a few other pictures of it, maybe the fracture has come from an overtightened bolt either through the head or the water pump housing.
good luck with it m8.
Sorry, you don't want to hear this but you CANNOT do an effective weld on grey cast iron because of the way the carbon atoms are arranged. Speroidal Graphite can be welded, but that's for use on cranks, not blocks. When you weld grey cast iron you just get cracks around the weld. There are plenty of books on the subject.
The other alternative is to get the block stitched, but it is expensive and there are many cheaper alternatives. I would source a replacement block, get it deburred and magnafluxed. Clean it, paint it and bore and hone the bores to the piston sizes you have.
I'd then just transfer everything in, reusing whatever you can.
The other alternative is to get the block stitched, but it is expensive and there are many cheaper alternatives. I would source a replacement block, get it deburred and magnafluxed. Clean it, paint it and bore and hone the bores to the piston sizes you have.
I'd then just transfer everything in, reusing whatever you can.
This explains it:
www.castironweldingrepairs.co.uk/machining_metal_stitching_castings.html
I should say that grey iron is hard to weld right and hard to get the material properties uniform.
If you google cylinder block stitching you get sites like this:
www.fjpayne.com/cases.htm
Basically, anything can be repaired, but you may need deep pockets to do so and a block sourced secondhand is going to be the cheapest route.
www.castironweldingrepairs.co.uk/machining_metal_stitching_castings.html
I should say that grey iron is hard to weld right and hard to get the material properties uniform.
If you google cylinder block stitching you get sites like this:
www.fjpayne.com/cases.htm
Basically, anything can be repaired, but you may need deep pockets to do so and a block sourced secondhand is going to be the cheapest route.
Cheers Gavin, welll the guy who rebuilt it is the one with the deep pockets as he is going to get the engine stitched now, and he is going to swallow the cost, so hopefully this will last the two seasons we need it for before it has a freshen and rebuilt anyway.
Will post here what happens!
Will post here what happens!
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