Author Topic: 71 Eldorado heat shield  (Read 120 times)

Offline NORTHPORTGUY

  • Posts: 75
    • CLC Member
      CLC Member #23013
  • Name: KEN WIEBKE
71 Eldorado heat shield
« on: November 14, 2017, 01:07:14 AM »
  i have a exhaust leak from twixt the engine and exhaust manifold.     while the exhaust manifold if off plan to remove as much as rust and treat to some manifold paint.  .    also plan to repaint the heat shield.  Was the heat shield painted originally? what do interested readers think about using the engine enamel on the heat shield  which while probably not stock will tidy-up the engine  bay appearance to me    i will have my trusty mechanic to the  actual work but while apart figured painting the manifold and heat shield  will make sense

Opinions observations are  most  welcome .  thanks

Ken Wiebke    CLC # 23013 
« Last Edit: November 14, 2017, 01:16:04 AM by NORTHPORTGUY »

Offline TJ Hopland

  • Posts: 6791
Re: 71 Eldorado heat shield
« Reply #1 on: November 14, 2017, 09:29:20 AM »
The heat shield may hold paint but I don't think it will be worth trying to paint the exhaust manifolds.  Paint burns off the exhaust ports on the heads fairly quickly and those run much cooler than the manifold.

Left manifolds on these really seem to like to crack so don't be surprised if you get it apart and its got a crack on the back side.  For sure give it a close look.  Ask your mechanic if he can or knows a shop that can 'surface' them.  These do seem warp so that will give you a better chance of sealing again.   Basically they just slap them on a big belt sander so it should not be that expensive or take that long.

Factory didn't use gaskets on these and if you are able to do both the heads and manifolds they do seal up good.  Without knowing the straightness of the head I would likely use gaskets but still surface the manifolds if possible.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline "Cadillac Kid" Greg Surfas 15364

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Re: 71 Eldorado heat shield
« Reply #2 on: November 14, 2017, 11:55:04 AM »
Ken
VHT high temperature paint works And has worked for me on exhaust mAnifolds and pipes IF you do the prep and let the paint cure.
Greg Surfas
Cadillac Kid-Greg Surfas
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline NORTHPORTGUY

  • Posts: 75
    • CLC Member
      CLC Member #23013
  • Name: KEN WIEBKE
Re: 71 Eldorado heat shield
« Reply #3 on: November 14, 2017, 01:03:38 PM »
  thank you.  i intend to install  individual gaskets i've heard a reference to "doughnut gasket"   see
 http://www.rockauto.com/en/moreinfo.php?pk=2186212&cc=1025851&jsn=398 

and have spent a C note on beautiful ss 12 point bolts. 

 with my luck surely the manifold will be cracked . VHT seems to have a good selection of manifold paints but sandblasting  required.  Greg did you use a primer too?   
I was not envisioning the cylinder heads being removed at his stage - the engine runs fine and don't want to open a can of worms. 
 I'm working w a type of mechanic who want to move cars in and out of his bay  so i'll have to work around that. to allow time for the sandblasting and surface preparation      looking at the VHT webpage see no specific cadillac blue but perhaps the flat blue sp11 will look good on the riser or maybe just flat black..  ..  good guidance   appreciated!                                                                                                                     

Ken Wiebke 23013 

Offline TJ Hopland

  • Posts: 6791
Re: 71 Eldorado heat shield
« Reply #4 on: November 14, 2017, 05:31:05 PM »
The doughnut gaskets are sometimes used for at the outlets.    The head to manifold are always flat like your link.

I would still try and get the manifolds surfaced especially if you are going to sand blast and paint them.  Get that done and then surface them that way no chance of damage to the sealing surface from blasting or paint to screw up the seal. 

You have to be careful with the hardware used for exhaust manifolds.  Too hard of a bolt will actually cause leaks because of the different expansion rates.  The bolts there have to be 'just right' so they can stretch as needed.    I learned that once because I bought grade 8 bolts at a hardware store.  They didn't have enough the same length to do both sides so one side was too long and I used a stack of lock washers to make it up.  The side with the lock washers held fine no leaks for the100K I had that car,  the side with just the bolts I constantly had bolts breaking and gaskets burning out.   The washers must have been soft enough to keep things happy. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline "Cadillac Kid" Greg Surfas 15364

  • Posts: 2773
    • CLC Member
      CLC Member #15364
Re: 71 Eldorado heat shield
« Reply #5 on: November 15, 2017, 09:40:03 AM »
Ken
If it is not too late I would find the actual source of the leak first. As mentioned previously the left Eldo manifold is crack prone. They can be fixed but it is usually less expensive to but a replacement. I've got a couple spares that I bought for my 72 so if it comes to that you can pm me. In regards to surfacing the manifold my machine shop (excellent shop that has successfully built many motors for me) dissuaded me from doing that unless I did the head surface as well.

Find the leak. If it is not a crack the standard one piece gaskets will work in 99% of the cases.
As far as finish, wire brush the primer with prescribed drying time then paint again allow prescribed drying time.
Greg Surfas
Cadillac Kid-Greg Surfas
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-