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crack in my head
Posted 26 October 2005 - 03:40 PM
I was cleaning the grime and left over head gasket material from one of the heads on my EA82. I was getting some of the charred carbon out of the depression where the valves are seated and then I noticed a little crack connecting the two valves. Both cylinders have them.
I already torqued the other head to the engine, but I don't recall them being the same way.
Is this line normal? In other words, is it where the metal was cast or something like that?
Or is this the kind of crack that should tell me to shop around for a new head?
I don't know all that much about engines, but I did build a VW engine some time ago that had a cracked head, and the crack went all the way through. In this case, there is just a line visible between the vavle seats and the rest of the head seems solid.
thanks in advance
Posted 26 October 2005 - 04:08 PM
From what I've read, hairline cracks between the valve seats are nothing to worry about. When the cracks are more than 1/32" wide, you have cause for concern.
To be really sure, you need to remove the valves and inspect the ports. If you see a crack inside a port, the head needs to be replaced.
Posted 26 October 2005 - 04:11 PM
Bridge cracks, as they're called, between the valve seats are perfectly okay as long as they're not huge or extend into the ports. Unless your engine was severely overheated or otherwise abused, you should be fine. If you've got a valve spring compressor, it wouldn't hurt to pop the valves out and have a peek in there. Another good idea is to take a small punch and tap the cracked portion a bit so it doesn't stick out in a sharp point, as that point can become a hot spot and lead to detonation.
This is a really common thing with the EA82s, and 9 times out of 10, nothing to worry about.
Posted 26 October 2005 - 08:13 PM
however between almost all the valves I have a very small crack that continues down that inner sidewall into the port. Most of 'em didn't weave to far down the port, a couple went a fair ways in.
i did extensive reading on this, yes the TSB too. The cracks in & around the immediate vicinity of the valves Do Not lead to internal coolant leaks. The jackets for coolant run more at the backside of the head, which is why you get bridge cracks in the first place (same with VW's). The dangerous cracks are those that can be found on the inside wall towards the outlet of the Exhaust ports. Cracks here will break into the water jacket and are what ruin the heads. Cracks up by the valves can't have this effect.. however I'm sure they eventually do have some ill consequence. To quell any doubt, take the head(s) to get pressure tested and that will determine the condition of your heads.
If you can access the exhaust outlet ports, use a toothbrush + degreaser and scrub away all the carbon and grime buildup. Use a stong LED light and look VERY carefully for cracks in and around this area.
needless to say, with me, I just punched down the topmost bridge cracks and reassembled the whole motor. I don't feel that they are gonna adversely affect operation, and sourcing new and/or better condition heads at this point wasn't an option.
good luck. if you search this forum you can find all the same info I did
Posted 26 October 2005 - 11:12 PM
Posted 27 October 2005 - 01:41 AM
Posted 27 October 2005 - 02:00 AM
I had mine pressure tested. Bridge cracks did not leak, exhaust port cracks did. Had to find another set.
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