Date:         Sun, 10 Oct 2004 18:20:43 -0500
Reply-To:     Jim Felder <felder@KNOLOGY.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Jim Felder <felder@KNOLOGY.NET>
Subject:      Re: '86 Westy Oil light flickers briefly...other basic ?'s
In-Reply-To:  <4168DB09.3070604@mchsi.com>
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On Oct 10, 2004, at 1:47 AM, Al and Sue Brase wrote:

> Jim:
>     Where did you get the 4k number?

The tach leaves the "green zone" about there, around 70 mph. It's a 
rough estimation of where the safe zone ends on the tach, it may be a 
little higher but it's not high enough, in my opinion, to do some of 
the speeds I hear about.

> I think the rev limiter comes on on 86-87's at 5400 rpm and 91's at 
> 5600 rpm. (I don't know about those years in between). That's also 
> about the same as the solid red on the tach, right? 7200 on a Porsche 

> must be a pretty short stroke one 2.0 or 2.2.

1977 2.7L, and yes the rev limited in the distributor cap certainly 
helped things. With the vanagon, I just have to watch it. If there's a 

rev limited on my 2.1, it's never been engaged.

> They've got rev limiters too, abeit a little cruder than the 
> integrated digifant ones. I don't think ANYONE was using "stretch 
> bolts" per se back in the 60's or 70's,
I thought racers and aircraft had always used them, but I don't know 
for sure.

> so I think the Porsche rod bolts are not quite the same thing. Maybe 

> "controlled stretch" is more appropriate. ( I'm VERY familiar with the 

> diesel head bolts- torque to increasing numbers in 3 levels, then do 3 

> steps of 1/4 turn each. I'm sure that a torque wrench would show 
> uniform torque at each step. It feels that way, anyhow.
Me too, I've had to do that on my diesel as well.

>      I guess I'm just taking the word of others like Bob Donalds, 
> about the stretch bolts, but damn near every 150k mile 2.1 is either 

> hurting or ventilated and VERY few 1.9's are.

The pistons are heavier, putting more stress on the rods at any given 
RPM.


> My own 2.1 spun a rod bearing at 90k miles. I put in a set of 
> reconditioned 1.9's and it has now done 55k miles since, some under 
> VERY high stress. Towed another Vanagon 400 miles in 90 degree temp, 

> towed other cars some at 75+ mph for thousands of miles. Still working 

> fine.

Like John R wrote, and as I have observed in m own cars, and as my shop 

concurs (they know how the owners drive each car and what the've had to 

do to those cars) my conclusion is that if you drive a vanagon under 70 

mph you can still do a lot of bad things to it, but you won't distort 
the rods. My vanagon has pulled a lot of weight in its day under a lot 

of conditions stressful to the engine, but it never has been driven 
over about 4K RPM. It has 190K on it, and it runs great, oil light 
never flickers, etc. etc. I've seen a lot of posts about using this or 

that oil, and this or that driving style, but I think it comes down to 

RPM and the stress on the rods. Rods out of whack (from either 
ovalizing or from bad bolts) would also explain some of the "I only got 

20K after a complete rebuild" stories I've heard.

>       In a previous life I reconditioned LOTS of Chevy rods using a 
> Sunnen precision hone and its various bits. Rods tend to go out of 
> round less after reconditioning. I guess the metal is sort of stress 

> relieved or hardened or something.
> Also, measurements at rest and measurement at 5400 rpm anre not 
> necessarily the same. Very likely it was underdesigned, but if the 
> better bolts help, I guess that works for me!

That's probably work-hardening, I guess. When I rebuild, I will use the 

best bolts I can get. But I will also measure the interiors of the 
crank journals on the rod, and if they're not round, I will toss 
them--my whole point from the beginning—because the new bolts won't 
correct the shape of a stretched rod any more than they would correct a 

bent one.

Jim
> Al Brase
>
> Jim Felder wrote:
>
>> My take on this is purely anecdotal, but I think that people who have
>> ovalized big-ends have been driving too fast for too long.
>>
>> Porsche 911s have stretch bolts on the big-ends, too, but they don't
>> "keep stretching." I got a lot more than 150K on a 911 and have a lot
>> more than that on my 2.1 now, and the oil pressure is good. I never
>> revved the 911 over 7.2K and don't ever rev the vanagon over 4K, the
>> intended redline for both. Anyway, if the bolts were to stretch you'd
>> have a double-radius circle with gaps where the separation was
>> occurring (where the cap fits) and it would be very easy to spot this
>> when the engine came apart. You would actually be able to put a feeler
>> gauge in the gap in between the cap and the rod body. Plus, I think
>> you'd definitely hear the racket and the oil pressure would drop to
>> zero in a big hurry as soon as a crack opened up.
>>
>> If the big-ends are becoming oval, I bet it's from either
>> under-designing the rod or putting more centrifugal force on it than 

>> it
>> was designed to have (running it over 70 mph, say). I doubt that the
>> bolts are stretching, though. If an inside micrometer or plastigage is
>> used to determine that a big-end is out of round, it's going to be out
>> of round whether the bolts have stretched or not, and will be out of
>> round no matter what kind of bolts are put back into it. It would be
>> the rods in this case, and not the bolts, that need replacing.
>>
>> Jim
>>
>>
>
>