Temperature of exhaust gas leaving the cylinder

lw395 said:
You can get a 10hp, electric start, water cooled Chinese diesel engine for about $300 apparently.
There must be some mileage in marinising one?
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I did wonder about that a few years ago. I think Northern Tool had some quite cute little recoil start 5hp ones and I half wondered about having a twin engine setup....
 
Avocet said:
Would anyone be able to provide any figures for the sort of temperature that the exhaust gas leaving my 10 horse, single cylidner raw water cooled diesel might be, please? I've had a bit of a bad evening today. I was taking the valves out of the cylinder head and just couldn't resist trying to chip a very annoying looking bit of flaky rust off the inside of the exhaust port. That was when my screwdriver went right through it and into the water jacket! It's a BMW D12, so there's no chance of sourcing a replacement head. They're just not available any more.

I was wondering about trying to clean the surrounding area with a die grinder and brazing a patch on. Daft idea?
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Brazing is not a good idea, the brazing will distort and crack. Specialist welding is a better bet. However, if you are thinking for a replacement, the small Chinese marinised diesels engine appear to be good value.
 
L
GEB said:
500 degrees centigrade is probably close - a 5500hp ferry engine, burning fairly heavy oil, operates at this temperature.

You may find a specialist repairer http://www.castironweldingrepairs.co.uk/
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Definitely worth asking this company, or one like them. I had a cracked cylinder head welded using this technique and it lasted well. Welding is carried out with the work red hot to take it above the austenitising temperature. This overcomes all the usual problems of welding and brazing cast iron.
 
vyv_cox said:
Definitely worth asking this company, or one like them. I had a cracked cylinder head welded using this technique and it lasted well. Welding is carried out with the work red hot to take it above the austenitising temperature. This overcomes all the usual problems of welding and brazing cast iron.
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Access might rule it out, but I'd also suggest having a metal spraying company take a look at it.
 
I have used a product called " J B Weld " to repair cracks in engines unbelievably it is a 2 part epoxy that is is stated to withstand 500 deg C have a look on youtube loads of engine repairs it only cost about £6 and you could shape a small overlapping patch of say 3mm thick plate on the water side of the repair also you could reinforce any thin material.
 
parbuckle said:
I have used a product called " J B Weld " to repair cracks in engines unbelievably it is a 2 part epoxy that is is stated to withstand 500 deg C have a look on youtube loads of engine repairs it only cost about £6 and you could shape a small overlapping patch of say 3mm thick plate on the water side of the repair also you could reinforce any thin material.
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Far to risky to use on the exhaust, which could easily see temperatures of 600C.
 
This head is actually cast iron in any case, but I had wondered about temperatures. The trouble is, with the curve of the exhaust port, the side with the hole will get the full blast of the hot gas as soon as the exhaust valve opens. I had wondered about trying to make a heat shield to deflect the worst of the heat (a washer on top of a washer, as it were).
 
The whole idea of the water jacket is to cool the hottest parts before they can be heat damaged so any patch would be water cooled to a large extent.
 
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.
 
parbuckle said:
The whole idea of the water jacket is to cool the hottest parts before they can be heat damaged so any patch would be water cooled to a large extent.
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That would depend in large measure on the conductivity of the repair. Whether it's 'High Heat' or regular JB Weld, it contains just 5-10% iron (and 10-30% limestone), so I can't see it being all that high.

According to their web site regular JB Weld "can withstand temperatures up to 550ºF". 'High Heat' JB Weld "is able to withstand continuous heat exposure of 400ºF and intermittent heat exposure to 550ºF". Note the 'F'. 550F is 288C. I didn't search the whole range, so perhaps you were speaking of a product with different properties?

If the OP's problem was a small hole in a car exhaust, maybe it would be worth the risk. But to fix a breach in a water jacket on a boat? Speaking personally: no (except perhaps as an emergency get-you-home, very carefully monitored). Apart from engineering issues, knowing what the OP knows (and having told the world), his insurer would have solid grounds for declining any claim consequent upon engine loss.
 
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Avocet said:
This head is actually cast iron in any case, but I had wondered about temperatures. The trouble is, with the curve of the exhaust port, the side with the hole will get the full blast of the hot gas as soon as the exhaust valve opens. I had wondered about trying to make a heat shield to deflect the worst of the heat (a washer on top of a washer, as it were).
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I humbly suggest to get some of the Bakerloc, use a couple of SS washers and a bolt thru with he resin on the waterside, think about it, up to 180c coolant? The washers will shield the resin from direct heat, the coolant will keep the resin at a reasonable temp
S
PS if you use a gasket patch under the washer/s on the hot gas side it is an insulator, Walkerite or Klingerit used to have asbestos in them. i might still have some in the garage, will look tomoz
Bakerloc specs


One (1) Bakerlok® kit contains:
- One (1) 8 oz per can of Bakerlok® thread-locking compound
- One (1) Hardener vial
- One (1) Applicator.
Features:
Withstands high breakout torque: (field trials in temperatures ranging from 50 C (122F) through 400 Celsius (752F) at the bottom of the borehole, showed Bakerlok® withstands superior torque loads, than a typical joint with 3-point welding with 2 inch beads.
 
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