Temperature of exhaust gas leaving the cylinder

Avocet said:
I understand what you're saying, but as there's a hole in it, even if the stuff was applied on the water jacket side, some of it would end up facing the gas coming out of the exhaust valve.
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I had a copper kettle that was ok if it has water in it but one day I let it boil dry and all the tin lining melted water is a great coolant.
 
Whilst cleaning an exhaust elbow on a Perkins Parama the screwdriver went right through the wall of the elbow,repaired it with JB weld,that was 5 years ago and still ok.
 
Yes, if this hole was after the water injection point, I would certainly use the JB (or a similar) product. In this case though, the problem is hat it's directly in the firing line of the hot gas leaving the cylinder.
 
Avocet said:
Yes, if this hole was after the water injection point, I would certainly use the JB (or a similar) product. In this case though, the problem is hat it's directly in the firing line of the hot gas leaving the cylinder.
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No the hole was before the water injection near to the bolt on flange,but mine doesnt seem to get that hot you can put your hand on it,problem may come if
I forget to open the seacock and it overheats.
 
Avocet said:
I understand what you're saying, but as there's a hole in it, even if the stuff was applied on the water jacket side, some of it would end up facing the gas coming out of the exhaust valve.
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I'm not trying to talk you into trying to do an epoxy job, but on the efficiency of water conducting away heat, even from something that is directly faced by the heat source... Try taking a blowtorch to a full plastic water bottle.
 
Woodlouse said:
I'm not trying to talk you into trying to do an epoxy job, but on the efficiency of water conducting away heat, even from something that is directly faced by the heat source... Try taking a blowtorch to a full plastic water bottle.
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Then try it on a thick plastic container. The problem is that while the water removes heat efficiently, the plastic is a good insulator, so while a thin plastic sheet will survive the blowtorch test, a thick one will not. What thickness of epoxy would be needed?
 
Woodlouse said:
I'm not trying to talk you into trying to do an epoxy job, but on the efficiency of water conducting away heat, even from something that is directly faced by the heat source... Try taking a blowtorch to a full plastic water bottle.
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Christmas day with a difference :-) off out to the garden with the kids...
 
JumbleDuck said:
Then try it on a thick plastic container. The problem is that while the water removes heat efficiently, the plastic is a good insulator, so while a thin plastic sheet will survive the blowtorch test, a thick one will not. What thickness of epoxy would be needed?
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You'd melt the outside of the thick plastic container but you still wouldn't be able to burn a hole through it whilst the water was behind it. Surely that's what matters here? As I said though, I'm not advocating bodging an exhaust port with epoxy, just saying that the epoxy is unlikely to melt away completely. I'd imagine epoxy is a relatively poor conductor of heat so a thin wall of epoxy might be better than a thick one.
 
I fancy the use of a countersunk head SS bolt with an SS washer on the gas side and another washer and nut with high temp époxy on the water side. Possibly a saddle made of a bit of SS tube to follow the curve of the port. The bolt would be cooled by the water and last until you decide on a replacement. The engine is a Hatz, also marinised by Renault. But I doubt that spares are common for those either.
 
Brazing would withstand exhaust heat and is commonly used to connect exhaust parts.

Cylinder heads can be successfully welded.

I've done both myself with complete success. I used nickel rods that don't require the object to be pre-heated.

There are a few youtube videos showing the technique.


Exhaust temperatures on diesels vary with load. We used exhaust thermometers to check load balance and valve condition etc.. As others have said, up to around 600 centigrade. How the weld would perform with seawater ( I see your engine is raw water cooled) I have no experience that comes to mind.
 
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Thanks gents. Bikedaft, how did the experiment go? So far, we've got (at full chat) the engine doing about 3000 RPM, so I'm guessing about 25 slugs of burning 600 degree C gas going past this repair every second. That sounds like quite a lot for an epoxy to take! It's not so much the heat as the "nakedness" of the flame that I wonder about. I've fired it up in the past without the elbow on for a few seconds and there were visible licks of flame coming out of the exhaust port...

I wouldn't go for stainless in electrical contact with cast iron. I was thinking more of a button-head carbon steel screw. (Button head to put a bit more thickness between the heat and the epoxy on the WATER side of the casting). Santa brought me my die grinder this morning, so I might pop out and attack the rust for a bit this evening and then see how big the hole ends up before there is sound metal around it. At present, a 6mm (shank) bolt would fill it nicely, but I know the metal at the edges of that 6mm hole is only a few thousandths of an inch thick. At present, plan is still a bolt, (with a washer if the hole gets bigger when I clean it up) and then exhaust bodging paste between the washer and the cast iron. then on the WATER side of the casting, another washer and nut (maybe with some of that "Bakerlok" stuff that Stu mentioned), and then a big blob of metal-filled epoxy over the nut and on to the surrounding cast iron.

Note, however, that this is still Plan B (Plan A being that second hand head in Australia that Prof Pat kindly found - although communications are proving a bit difficult. hopefully, that's just 'cause it's Christmas)!
 
prof pat pending said:
I guess this depends on how much you want to keep your original engine?

http://www.ebay.com.au/itm/BMW-D12-...=AU_Car_Parts_Accessories&hash=item2a48fd5180
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Well, it's finally arrived!!!! Bit of an emotional rollercoaster! Seller seemed like a really decent chap but various problems with eBay over splitting the stuff that he had for sale (I have an external alternator and didn't want those bits) held things up for a bit. These were eventually overcome and it was posted on 31/12. Actually got as far as Coventry by 04/01 which I thought was pretty impressive, but then languished there for over a week at HM Customs' pleasure while they worked out how much to fleece me for Import Duty and VAT! Top tip for anyone else thinking of buying from outside the EU and using airmail (from one who has just learned the hard way!) is that the gits charge Import Duty on the item but then 20% VAT on the item plus import duty PLUS POSTAGE!!!! (Oh, and a £14 "handling charge"...

Anyway, having got that off my chest, this thing looks truly excellent! I've used some bent calipers to measure the wall thickness in a few places round my existing head and I'm getting 1.95mm, 1.44mm and 1.06mm. (and, of course, one bit where it's "0mm")! The same areas on this "new" head are 3.59, 2.96 and 4.32mm respectively, so I'm chuffed to bits at that!

Can't thank you enough for spotting that one Prof - I owe you a virtual pint (or maybe even keg...)!
 
Avocet said:
Anyway, having got that off my chest, this thing looks truly excellent! I've used some bent calipers to measure the wall thickness in a few places round my existing head and I'm getting 1.95mm, 1.44mm and 1.06mm. (and, of course, one bit where it's "0mm")! The same areas on this "new" head are 3.59, 2.96 and 4.32mm respectively, so I'm chuffed to bits at that!
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Hooray. If the new head is significantly eroded below original spec in any of these places, this might be a good time to have built up with welding/spraying ...
 
"
Avocet said:
Well, it's finally arrived!!!! Bit of an emotional rollercoaster! Seller seemed like a really decent chap but various problems with eBay over splitting the stuff that he had for sale (I have an external alternator and didn't want those bits) held things up for a bit. These were eventually overcome and it was posted on 31/12. Actually got as far as Coventry by 04/01 which I thought was pretty impressive, but then languished there for over a week at HM Customs' pleasure while they worked out how much to fleece me for Import Duty and VAT! Top tip for anyone else thinking of buying from outside the EU and using airmail (from one who has just learned the hard way!) is that the gits charge Import Duty on the item but then 20% VAT on the item plus import duty PLUS POSTAGE!!!! (Oh, and a £14 "handling charge"...

Anyway, having got that off my chest, this thing looks truly excellent! I've used some bent calipers to measure the wall thickness in a few places round my existing head and I'm getting 1.95mm, 1.44mm and 1.06mm. (and, of course, one bit where it's "0mm")! The same areas on this "new" head are 3.59, 2.96 and 4.32mm respectively, so I'm chuffed to bits at that!

Can't thank you enough for spotting that one Prof - I owe you a virtual pint (or maybe even keg...)!
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A result! excellent, dont poke it!
S
 
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