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What ever happened to the idea of peening the pre-cups?
by
Dakotakid
on 15 Apr, 2015 20:16
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I can remember (about 6 or 7 years ago) (on this forum) that the concept of attempting to "anchor" the pre-cups, in older heads, by multiple peening marks......was all the rage. I mean there used to be photo after photo of this "black art."
It was right up there with Frisbees, Hula-hoops, and Ford Pintos. I mean to tell you, it was the "default" answer for everything from dead batteries to ash trays that needed emptying.
Then, all of a sudden it was like Bill Clinton.
When did this "technique" fall out of favor? I ask because of the one guy who was ether-ing his Parts Place head and going to run it.
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#1
by
theman53
on 16 Apr, 2015 06:13
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I gave up on it as I peened mine and a cup still fell out.
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#2
by
libbydiesel
on 16 Apr, 2015 07:46
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I believe that the cracks are more of an issue. If a pre-cup is solidly peened in place but cracks in half it will destroy the engine. At this point I thoroughly inspect every pre-cup before install and replace any that have even micro-cracks. That said, if a pre-cup is not tight in the bore it can wiggle and destroy head gasket, pre-cup bore and top of piston (I've seen it more than once). If any precup is loose in its bore, I will peen to make it fit tightly. At this point I also believe that having the precup protrude above the head so it is pinched tightly by the head gasket.
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#3
by
745 turbogreasel
on 16 Apr, 2015 12:46
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. At this point I also believe that having the precup protrude above the head so it is pinched tightly by the head gasket.
I am on this bandwagon as well. I also think using a cutter to surface the head with them in eggs the precup bore.
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#4
by
theman53
on 16 Apr, 2015 15:48
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To add, 1 fell out the other 3 of mine could move in and out of their bores with just finger nail grabbing onto them. Heat and time or ether heat and no time is really bad for them.
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#5
by
vanbcguy
on 16 Apr, 2015 18:03
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Large part of why I went M-TDI....
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#6
by
libbydiesel
on 17 Apr, 2015 10:55
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The absence of pre-cups is a big plus. I also like the 15% better fuel economy.
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#7
by
RabbitJockey
on 17 Apr, 2015 11:35
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is it really a 15% difference in fuel economy? i always read 10-15% better engine efficiency, but thats before all the accessories and the drive line and aeodynamics.
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#8
by
libbydiesel
on 17 Apr, 2015 19:08
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I dunno. It's at least 10%. I've never driven the same car with both engines at the same acceleration rates.
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#9
by
vanbcguy
on 19 Apr, 2015 09:08
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I'm definitely getting quite a bit better economy with mine. Went from a 1.6 TD to an M-TDI. Last highway trip I did was 5.2l/100km, same trip on the same road at the same speeds with the same car used to be more like 6.5l/100km.
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#10
by
libbydiesel
on 19 Apr, 2015 12:21
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Yes, I know I have gotten at least 10% better fuel economy but I also know that I haven't run a tank where I haven't accelerated a lot faster at least a few times, so I'm not sure what the actual % is if you do the same acceleration rates. It's kinda fun to think that my mTDI vanagons consume the same amount of fuel as a 1.6 non-turbo vanagon which was probably the slowest production vehicle in the last 50 years... I think I could probably tow a second vanagon with mine and still accelerate faster and have a better top speed.
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#11
by
RabbitJockey
on 20 Apr, 2015 09:47
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Yes, I know I have gotten at least 10% better fuel economy but I also know that I haven't run a tank where I haven't accelerated a lot faster at least a few times, so I'm not sure what the actual % is if you do the same acceleration rates. It's kinda fun to think that my mTDI vanagons consume the same amount of fuel as a 1.6 non-turbo vanagon which was probably the slowest production vehicle in the last 50 years... I think I could probably tow a second vanagon with mine and still accelerate faster and have a better top speed.
i can't believe they ever sold them like that.
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#12
by
RabbitJockey
on 20 Apr, 2015 09:54
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Yes, I know I have gotten at least 10% better fuel economy but I also know that I haven't run a tank where I haven't accelerated a lot faster at least a few times, so I'm not sure what the actual % is if you do the same acceleration rates. It's kinda fun to think that my mTDI vanagons consume the same amount of fuel as a 1.6 non-turbo vanagon which was probably the slowest production vehicle in the last 50 years... I think I could probably tow a second vanagon with mine and still accelerate faster and have a better top speed.
i can't believe they ever sold them like that.
i guess 10-15% isn't that crazy of a difference either, say in a jetta u get 45mpg with a 1.6td, with a tdi u should get 50-53