-
Scored Piston and barrel - 1.9 AAZ Vanagon
by
Gizmoman
on 04 Aug, 2012 15:38
-
I am rebuilding my 1.9 due to what appeared to be a blown HG - never saw positive sign of that but I did have a loose pre-cup on # three and the others were a bit loose as well.
Today I got into the bottom end and pulled the pistons. All look quite good with the exception of #4.
Both the barrel and the piston are scored
.
The bore is stock 79.51mm and all other barrels look good (however, if there were ever hone marks, they are gone) but #4 is scored down both sides (front and back) and I doubt a hone would clean it up. The top ring on #4 piston is sorta jammed into the groove. My guess this thing just got a bit too hot? What else could have caused this?
Some of the scoring actually may be some aluminum from the piston and if I were to hone it, that would go away. In other words, possibly honing is worth a try.
If anyone knows of a good shop here in San Diego, please let me know. Also, any recommendations on high quality rings and pistons would help.
Thanks
-
#1
by
Jarrus
on 04 Aug, 2012 17:29
-
Maybe lack of lubrication in a previous life?
-
#2
by
theman53
on 05 Aug, 2012 06:27
-
I would say this is further evidence that it was ran really hot, high egt's. The precups don't come loose with out that heat and it looks like the piston grew too much for its bore. If it has been ran like this I would recommend the shop taking a look at it.
-
#3
by
Gizmoman
on 05 Aug, 2012 07:36
-
Yeah, I agree, defiantly got toasty in there!
I'm wondering if a plugged oil squirter on 4 could cause this as it's only #4 - the other 3 look just dandy - I would think 2&3 would be the first to go. Any thoughts?
You'd think I would have know better turning up the fuel and boost with no IC or EGT - well, I know now
-
#4
by
theman53
on 05 Aug, 2012 08:05
-
It is a possibility that the oil squirter was messed up, but IIRC they usually stick open not closed. Not sure on that one.
Another idea is that #4 fuel injector could have been messed up. Bad atomization causing hot spots.
-
#5
by
Gizmoman
on 05 Aug, 2012 08:47
-
Ok, That makes sense (you usually do
)
While I'm putting my list of needed parts together I am also going through the K14. In the FAQ, there's tons of great info and a lot of it is from you. In particular, I need to remove the waste gate (customized an Allen wrench already) and I have it loose.
Getting it out though seems impossible. The post in the FAQ says
So following Andy2's advice, I slide hammered those heat shields out of there! Here is what it looked like when they came out... lots of carbon built up:
Does he mean he used the waste gate housing as a slide hammer? Should I heat the housing up? This thing is really stuck - looks like " the heat shield is part of the casting.
Any advice appreciated.
-
#6
by
theman53
on 05 Aug, 2012 08:52
-
I did that and used the wastegate housing as a slide hammer. For the time and hassle involved send it to those guys in Ohio that rebuild the turbo for 225.00
-
#7
by
Gizmoman
on 05 Aug, 2012 09:00
-
Right after I asked, I went back and got after it - came right out after about six "hammers".
Defiantly couldn't have been seating too well on that bet of carbon.
I'll take your advice about sending it out. Hope they don't charge extra for getting a box-o-bits
-
#8
by
libbydiesel
on 05 Aug, 2012 09:57
-
Another possibility is that the exhaust or intake valve on that cylinder leaked and let out the boost air. The resulting over-fueled situation got the piston too hot and it started to melt. That would be pretty easy to check. Tip the head on it's side with the ports up and pour/spray some solvent in there. If it leaks out on the combustion face, your valves were leaking. Any impressions on the piston tops?
-
#9
by
Gizmoman
on 05 Aug, 2012 13:52
-
OK, I did the leak test and it appears to be bleeding a bit out around both valves. As to "impressions on the piston tops" - I did notice some fairly large chunks - yes chunks of carbon in the intake ports. Some of this stuff is quite hard and there are some
tiny marks on top of the piston near the edge. It actually looks like a few bits of carbon broke loose and may have gotten in there (as if could go anywhere else
). The piston sides look like someone tossed in a few large grains of sand. Could bits of carbon do this and why would I have carbon on the intake ports anyhoo?
I 'spoze from leaky valves?
Right now the carbon is crusty but not as hard as sand. I wonder though what i's like when it's really really hot.
-
#10
by
Gizmoman
on 06 Aug, 2012 19:34
-
I think I found a decent local machine shop to do the block boring. They say they specialize in Diesel engines.
Before I take it in to them, what would be a decent price to expect to have them just bore all four barrels to one size over from stock.
Any advise on what I should ask about - special things to consider, etc?
I am also looking at Hans pistons. I've heard they are pretty good but that I should get rings somewhere else. Any suggestions?
Thanks
-
#11
by
CrazyAndy
on 06 Aug, 2012 19:54
-
AS far as the machinist price, I can't help you there. Prices do vary moderately, though.
As for Hans (aka Prothe) pistons, yes you can use the pistons but don't use the rings. Too many folks have reported excessive consumption post-break in. Stop by your local NAPA and order some OS Goetze's.
-
#12
by
Gizmoman
on 06 Aug, 2012 23:14
-
Thanks Crazyandy - much appreciated. His pistons look 1st class in the photos and with what appears to be an anti-friction coating on the skirts. I noticed on the Goetze website they make metal head gaskets as well probably spendy but a wise investment.
-
#13
by
theman53
on 07 Aug, 2012 05:39
-
Just remember that "specializing in diesel" doesn't mean they know about these engines. My last machinist did reluctanly bore to the .001" size bigger than the piston. But he didn't want to as he said most diesels were bored to around .003"...that is the wear limit of our engines. I would check out the bently and ask them many questions about what their plans are to do, if you know what is expected then you will know what you need to hear. If they argue and won't do it as the bentley says then leave and find one who will. Also have your pistons in hand when boring, I wouldn't trust a shop that didn't bore to the piston and just went with a .020" over stock as some pistons measure differently.
-
#14
by
Gizmoman
on 07 Aug, 2012 17:07
-
Excellent advice theman53, will do.
After doing a search on Gotze rings, I found some very unhappy guys who get wide ring gaps using them - even after several attempts. One poster said he goes one size over and files them to the proper gap.
I believe you have been involved in several of these discussions as well. What is your opinion?