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TrollFromDownBelow Samba Member
Joined: January 04, 2005 Posts: 414 Location: Metro Detroit
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Posted: Tue Jul 10, 2018 7:47 pm Post subject: type IV engine refresh conundrum... |
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Long story short...have a really good running bus - smooth, not flogging it to keep up with traffic, will do 65-70 (real speed) all day long. But...one head has a broken exhaust stud...ergo, not fixable. Other head has a healicoil of unknown origins that has a death grip on the plug; I've put 20k on that plug myself (bought the engine used...no telling how many miles on the plug), and it's down to the nubbins. I checked compression about 10k ago, and it had 110-118 on the three cylinders I could check (sans helicoil cylinder). It's always been a bit thirsty for oil. about 300 miles per quart interstate and 600 or so city.
Got tired of the noisy exhaust, and finally broke down and bought a set of Len's heads .
Took the engine apart last week, and based upon pooled oil on the jugs and slightly washed off carbon on the piston, I've got blow bye issues.
Complete tear downs is not in the cards right now, mainly due to time constraints (short summers here in Michigan, still want to get some use out of it this year), and, as I only put a couple thousand on it a year, if I can get it to go another 15-20k miles, that's a good bit of time.
My theory is, if I re-ring and hone the cylinders I won't disrupt the inherent balance/homeostasis of a nice running engine, and will probably get another 20k.
Alternatively, I could put new pistons and jugs on it, although it may run phenomenally, as I won't be able to balance the assembly, I'm concerned that it will start beating things up internally and I will have even less time before a total rebuild.
Goal is to get as many reliable miles (oil burning be damned) in it's current state before having to do a total rebuild.
Bottom line, which option is more likely to give me more miles before I have to crack the case apart? _________________ 1976 Westy (aka Tripod)
2.0 liter FI solid lifters
212k miles |
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busdaddy Samba Member
Joined: February 12, 2004 Posts: 51149 Location: Surrey B.C. Canada, but thinking of Ukraine
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Posted: Tue Jul 10, 2018 8:58 pm Post subject: Re: type IV engine refresh conundrum... |
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Photos of the bores with the pistons down at the bottom of thier stroke would help decide, and measurements of the piston and ring land clearance.
How was the oil pressure pre teardown? How long did it take for the oil light to come on after you stall it when warm?, what weight oil were you running?
What's the endplay like?, how do the lifters and cam lobes look?, what does it look like down the breather tower? _________________ Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50351
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Posted: Tue Jul 10, 2018 9:04 pm Post subject: Re: type IV engine refresh conundrum... |
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What does your cam look like? If the cam and lifters are badly worn then nothing you do to the rest of the engine is going to give you a long lived engine.
I doubt you will end up with more cylinder taper than the POS engine I have in my Bay presently. I have about 20K miles on it since I honed the cylinders and replaced the rings and it runs as well as can be expected with a sad excuse for a cam. I figure it will give me another 20-40K miles before the pistons decide they have had enough. |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21519 Location: Oklahoma City
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Posted: Tue Jul 10, 2018 9:35 pm Post subject: Re: type IV engine refresh conundrum... |
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Wildthings has noted the most critical issue.
As for cylinders....honing and new rings...whether its just a new cross hatch with a FlexHone....or a rebore on a machinem...are NOT simple work.
I would have at minimum....a good basic valve job done if you have no cracks.....and pjt ib real inserts and post about it because we can help you do better than a helicoil.....and buy a new set of cylinders and pistons.
Also.....the piston balance unless they are grossly off......are the least of the balance issues. If you are leaving the bottom end alone....and assuming the end for end balance on the rods is ....ok......asong as the pistons are not more than a gram out each from the old pistons.....just reuse the old wrist pins in the same position. Ray |
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Spike0180 Samba Member
Joined: June 06, 2015 Posts: 2269 Location: Detroit, Michigan
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Posted: Wed Jul 11, 2018 5:04 am Post subject: Re: type IV engine refresh conundrum... |
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raygreenwood wrote: |
Wildthings has noted the most critical issue.
As for cylinders....honing and new rings...whether its just a new cross hatch with a FlexHone....or a rebore on a machinem...are NOT simple work.
I would have at minimum....a good basic valve job done if you have no cracks.....and pjt ib real inserts and post about it because we can help you do better than a helicoil.....and buy a new set of cylinders and pistons.
Also.....the piston balance unless they are grossly off......are the least of the balance issues. If you are leaving the bottom end alone....and assuming the end for end balance on the rods is ....ok......asong as the pistons are not more than a gram out each from the old pistons.....just reuse the old wrist pins in the same position. Ray |
He bought new Len Heads.
I don't think it would make much of a difference. If you buy new pistons, get your hands on a good food scale and make sure each piston is the same weight as what came off the engine. If not the same as what came off, then at least make them equal to each other. Or just hone and rings, slap it back together and go back in this winter. Either way, make sure to glance at your cam lobes for wear. Likely they are worn if it wasn't a recent rebuild. _________________ Brutis Patches Izabich: 1970 VW Transporter - 1776cc DP
Current State: Projects never truly end...
Location: Grosse Pointe, Michigan
Other cars: 2003 F150, 2003 Jetta GLI vr6-6sp
Sambastic: adj; the quality of being nit picky, elitist, expecting everyone to do things the way they believe is best with no regard to situation, "sambastic" |
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my59 Samba Member
Joined: August 13, 2003 Posts: 3793 Location: connecting the dots
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Posted: Wed Jul 11, 2018 3:44 pm Post subject: Re: type IV engine refresh conundrum... |
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If you already have the engine out, the heads off, and willing to do new P&C, then review the cam and as they say, in for a penny, in for a...rebuild.
Dunno what your work space is like, but a rebuild in my barn in the summer is very preferable to the rebuild I did over the winter a few years back, no heat, layered up, and moving parts from the barn to the basement to do measurements, figuring parts at 30 degrees will be different than parts at 68 degrees...
The cam wear was pretty spectacular, the lifters were dished and the engine had almost 0 oil pressure before it was pulled. _________________ my59: Well son, my grandfather died before I got to drive it, so does that answer your question?
our79: sunroof bus w/camper interior and 2.0 FI
Other:'12 Jetta, '77 Benz 300D, and a 74 MG Midget. |
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Tbob Samba Member
Joined: May 26, 2007 Posts: 417 Location: Pensacola, Fl.
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Posted: Wed Jul 11, 2018 7:29 pm Post subject: Re: type IV engine refresh conundrum... |
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I feel your pain. The midwest with it's 4 seasons (June, July, August and Winter) make it hard on car hobbists . You either have time to work on it or drive it before the next winter. I also understand your dilema, you had a good running bus with head issues that were secondary to proper combustion events. So new heads, and re ring and hone, should be able to get you another 20,000 miles, right? Re read Bus Daddy's post . If you had good oil pressure before teardown, and your endplay was within range (both indicators of an ok bottom end), if your cam and lifters are ok(Highly unlikely), then I would pull the oil pump and make sure the idler shaft hasn't migrated toward the cam, Also check that the cam rivits are tight, and that the cam doesnt have excessive end play, indicating a bad thrust bearing. If all checks out well, then check the cylinders and pistons carefully, as a quart every 300 miles is a lot of oil usage. New pistons and cylinders may be warranted. You may get lucky, and be rewarded with that 20,000 to 30,000 miles you are hoping to get.
Although my old Fords will run an amazing amount of time with really make do repairs, our air cooled engines do not seem to be as tolerant of partial repairs.
A few years ago, I pulled the engine on my 73 to do a clutch. I was taught to do a simple compression test before pulling any motor, and cyl #3 was 75 lbs where all others were 120-125. I found a bad head gaslet, and almost would have put the engine back together except when I spun the reassembled long block around on the engine stand, I heard the unmistakable sound of a loose piece of hardware rattleing around in the case. So, I took it all apart. Never found the source of the sound, but i did find the oil pump idler shaft hitting the cam, and almost wearing the heads off the rivits, the distributor drive had too much play, and one of the cam bearings was eroded.Of course, the cam and lifters were shot. Like you, my engine ran great, and smooth. But it was a time bomb. _________________ 1969 Deluxe, owned since 1973
1973 Westfalia, owned since 1983
1980 Westfalia, watercooled conversion
1985 Westfalia, stock!
1986 Westfakia, Audi I-4 conversion
A couple of trucks and a couple of Jeeps |
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