cracked frame

I have an '86 Chevy pickup. I live in north Texas and the last 2 days went below freezing, I only had water in the radiator. I checked the fluid and I have oil in the radiator. I do not have oil in the crankcase. I am
hoping it is a head gasket or something, because I have drained it a few times now and it is clearing out. Would the heater affect this, maybe it runs through a different gallery or something, because I stopped using the heater and it seems to have gone away. How can I check to see if I may have cracked the block or heads cheaply? Also, when I found out this, about the oil in the water, I also found out that my frame rail is cracked completely in two just aft of the passenger side motor mount. Is there a cheap repair for this? Do I need to weld the seam and then put braces on both sides?
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if you weld it, you MUST use fish shaped plates over the crack . they are just oblong plates with a triangle shaped cut on each end. This will prevet a new crack. old john

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On Sun, 11 Dec 2005 18:22:07 -0800, ajeeperman wrote:

John, to clarify, do you mean plates shaped like this? ________________________ \ / \ / \ / / \ / \ /______________________\
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Warren Post
Santa Rosa de Copán, Honduras
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Having a mechanical engineering tech background, you are going to have to explain that one.
Steve
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Steve Mackie wrote:

It's called a double 'fish mouth' shape and it prevents a major discontinuity
in structural stiffness.. The fish mouth shown/could have a deeper
triangular trim.... and pulled back from trim corner weld ends may help too..
A discontinuity in stiffness may cause a Stress concentration.....
And major stress concentration can cause a metal fatigue crack...
Retired, ME
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Did I mention I graduated first in my class, with honours. You didn't need to explain what a stress concentration can do.
Do you know of any reference texts on this "double fish mouth." I don't see it in any of my texts and I'm interested in it. I've joined a many of tubes/channels/etc. on paper and have only used flat plate. I just want to read up on the application theory.
Steve
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Steve Mackie wrote:

Fishmouths & shear ties are a way to blend stiffness between a box section
and a channel... which minimizes stress concentrations... Metal shape
as well as weld & weld ending details become equally important.
I've done this work in my younger Engr days via MTS test equipment, finite
element modeling, and PVC scale plastic modeling using Stresscoat paints.
It is a self acquired design/Engr skill that is used to solve structural Problems.
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You just seem to be stating the same thing over and over. I have never used anything but plain rectangular plates and they have always met stress requirements. I want to read into the theory to see if changing the way I do it is worth it.
Steve
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Steve Mackie wrote:

I know of no particular papers nor books on the subject, but
Technical Topics that may cover the general issue are:
Theory of Reinforcements...... or
Designing for Fatigue..... or
Lightweight Structure Design......... Amen
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On Wed, 14 Dec 2005 11:40:14 GMT, "Steve Mackie"

I have looked and looked for information on the NET about fish mouthed re-inforcing plates and there isn't much to be had.
Basically you can use a plate cut to form what looks like an open fish mouth on each end.
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You can also use a diamond shaped plate to give the same effect.
To weld the frame directly from the top to the bottom makes it likely to crack again for reasons which I am not qualified to try and explain. After over 30 years of working as a Millwright, I can say that once a crack has been welded it quite often cracks there again so a plate is used to bridge the repaired area and this plate is welded with stitch-welding so as not to make a continuous weld. This way, if one stitch was to crack it won't carry over to the next weld. The fish mouth (or diamond) allows you to place welds that are not in a direct line from top to bottom.
Since my explanation is wanting, and I am just a DIY repairman, I have cross posted this message to a welding NG to draw in some expert opinions for you - and for me :)
--
Gordie

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jmar595 wrote:

I do not have oil in the crankcase.
WHY ?
I am

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I think he meant no water in the crankcase :^), but oil in radiator, If this is the case, I would suspect a leaking transmission oil cooler in the radiator, not a engine oil leak. Engine oil in Radiator will always result in antifreeze in the crankcase..
JJ

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02B12S wrote:

Then he should have antifreeze in the Tranny fluid also

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cracked intake ?...

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02B12S wrote:

    Not always so. If you have a radiator with a engine oil cooler in the side tank. The oil cooler can leak/seep oil in to the cooliant, and not suck cooliant back in to the oil cooler.
    Had this happen on a 1993 Buick Regal with a 3.8 V6. Charles
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Yes, I meant no water in the oil, sorry. I have a granny 3 speed so I don't think it is the oil cooler, don't think there is one. I did a compression test last night and it went like this... #1- 150 psi, norm plug, #3- 135 psi; norm. plug; #5- 135 psi, norm. plug;#7- 135 psi, norm. plug;#2 145 psi, norm. plug; #4- 135 psi, noprm. plug; #6- 85 psi, norm. plug;#8-120 psi, oily fouled plug. With this do you think it is possible I have a blown head gasket between 6 and 8?
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jmar595 wrote:

With Both Valves closed .. Piston on the Down stroke. Remove the Radiator Cap, Pump Compressed air into that Cyclinder Via the spark plug Hole. If the Head gasket is leaking u will Get Bubbles showing up at the RADIATOR cap HOLE in the radiator .

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Is the truck in fantastic shape, other than the issues you've mentioned? If not, it may not be cost effective to invest a lot of time and money to repair a cracked frame and engine in a truck that's 20 years old. Take a few minutes to do the math before you start throwing your hard earned bucks into a money pit.
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