head gasket

[64von]

I bought a 1964 with 37000 actual miles I believe to be true. I had a miss issue at any thing more than idle. I pulled plug wires off one at a time and found that all three cylinders on the right when I pulled the wires didn't make much difference to the way it idled. did a compression check and had very little PSI on all three cylinders. ran each one to TDC and I can hear air blowing from some were around the jugs on all three.

What is the chance that all three head gaskets being blown? Thanks in advance

[azdave]

What is the chance that all three head gaskets being blown?

I would say extremely rare unless a rookie had removed the head and re-installed it incorrectly. More likely to be multiple valves not closing fully due to gummed up guides or poor adjustments. Have you looked under the valve covers at the rockers or valve stems? Performed a leak-down test? A leak-down test on each cylinder at TDC will help evaluate leakage past the valves, rings, holes or cracks in pistons, etc.

[bbodie52]

Welcome to the Corvair Forum!

It might be that whoever assembled the engine forgot to insert the head gaskets on one side before installing the head. It may become necessary to remove and inspect the head and cylinder mating surface for damage or missing head gaskets (or perhaps stacked head gaskets when the originals had not been removed).

Low cylinder compression and air escaping from the head gasket area is a significant clue. A leak-down test (if you have access to a full-sized air compressor and the needed tools) might confirm where the air is leaking from (past rings into the crankcase, past intake valve(s) into the intake manifold, past exhaust valve(s) into the exhaust system, or past the head gaskets). Or, if you are pretty sure that the head gaskets are the leak source, you may just opt to pull the cylinder head and look.

A healthy engine would have compression readings close to 130 PSI with all cylinders within 20 lbs of each other. With a low cylinder reading of 87.5 and a high of 105, your test meets the 20 PSI maximum range limit (barely), indicating a fairly even pattern of wear, but quite a bit below the 130 PSI standard. You might try a different compression test tool to see if it shows similar numbers, and make sure the carburetor throttles and chokes are wide open when performing the test to obtain the highest readings. If the average remains low, a cylinder leakdown test can tell you more about the nature of the worn components (bad piston and rings/cylinder barrel wear, bad cylinder head valve seal, etc.)

A cylinder leak down test is a more advanced diagnostic procedure, and little more difficult to perform, because it requires some fabricated plumbing or a special test instrument, and a large capacity air compressor. Each cylinder to be tested is set at Top Dead Center (TDC) on the compression stroke (both valves closed). External air pressure is applied through the spark plug hole, and the percentage of leakage is evaluated. The source of the leakage (intake valve, exhaust valve, cylinder head gasket, or piston/cylinder seal) can be determined using an automotive stethoscope to listen for the leakage path (intake manifold, exhaust manifold, or crankcase). This test is performed on each cylinder, to determine the mechanical seal and condition of each cylinder. A video demonstration of this process (in this case, using a Volkswagen engine) is shown below.



There are many leak down testers available on Amazon.com. An example is shown below...



OTC 5609 Cylinder Leakage Tester Kit

4½ Stars out of 5 with 807 customer reviews | 75 answered questions

Price: Price: $73.31

http://www.amazon.com/s/ref=sr_st_revie ... eview-rank

A decent mechanic's stethoscope can be had for about $15.00...



Also helps to locate noisy idler bearings, blower bearings, etc.

OF COURSE, A PURCHASE OR A RENTAL WILL DO YOU NO GOOD IF YOU DON'T HAVE ACCESS TO A DECENT AIR COMPRESSOR WITH ADEQUATE CAPACITY.

The link below will provide you with a list of useful websites that are Corvair-related. Some of the links will lead you to an extensive technical library that will allow you to download shop manuals and other technical references in Adobe Reader format at no cost. There is also a link that will help you to locate nearby CORSA (Corvair Society of America) club chapters. You will also find a list of essential Corvair parts suppliers. Clark's Corvair Parts in Shelburne Falls, MA is the biggest and oldest Corvair supplier in the world. You will find a link that can provide you with a series of videos that amount to a tour of the Clark's Corvair Parts facilities. I think you will be amazed at the quality of the reproduction components they offer — particularly the interior carpeting and re-upholstery items. Parts suppliers such as this truly make our Corvair hobby possible.

Common and Useful Corvair Websites

viewtopic.php?f=225&t=6007


I would like to encourage you to expand on your earlier post and tell us more about yourself, as well as about your Corvair. Some detailed photographs of the car — including the VIN and Body Tags in the engine compartment — can be very helpful. If you can provide your personal assessment of your mechanical skills and abilities, that would help a lot. Members of the Corvair Forum love to be helpful in assisting other Corvair owners with technical support and advice, but it helps a lot if we have some understanding of your technical background and mechanical abilities, your Corvair-related knowledge, etc. Helping us to know more about you will help us to write comments to you that are tailored to your needs and experience. If there is a CORSA club chapter near you, contacting local like-minded Corvair owners can add a great deal with their local support knowledge, assistance and advice. Please let us know what town or area you live in, as this information can often suggest some helpful solutions.

[64von]

HELLO I was asked to give some back ground . So am 59 years old I live in Missouri. I have been in industrial maintenance my whole adult life. I am currently a maintenance manager for a large factory . I recently purchased a 1964 two door Corvair with 3700 original miles I believe to be true. I got interested in Corvair because my dad had two of them when I was growing up. Like I said in earlier post I have a miss on all three cylinders on the right and suspected bad head gaskets . So tonight I put ATF fluid in the cylinders and put 75-100 PSI to them with the valves closed and all I got was a mist of oil coming out of the top of the head but not bad so no blown head gasket. Later this week I am going to swap the carburetor’s from side to side. Also do a compression test. Thanks in advance for any help

[joelsplace]

"a mist of oil coming out of the top of the head"
What does that mean?

[64von]

So I put ATF fluid on top of the cylinder to help find where it was leaking. So when I pressurized the cylinders with 75-100 PSI of compressed air I assume some was leaking by the pistons and turning into mist and coming back out the push rod tubes. A little not

[azdave]

Later this week I am going to swap the carburetor’s from side to side. Also do a compression test. Thanks in advance for any help

Why swap carbs side to side if you have no compression on all cylinders of one bank? You are chasing low compression, not bad carburetor issues. Why do another compression check (unless you have made adjustments you have mentioned)?

Compressed air getting past the rings and ending up in the crankcase (then out the pushrod tubes) doesn't really tell us much because it can't be quantified. It could be normal leakage or you might have multiple holes in your pistons. Back out the 6 rocker nuts slightly on that bank until about 2 threads are showing and then try a compression test again. If still zero, then a leak-down test will help identify what percentage of air is being lost and you will be able to hear if there is air leaking past the valves (listen for air escaping from the intake or exhaust) or the crankcase (listen or feel for air coming out of the oil fill tube when the cap is removed). You might also do a leak-down test on the other bank (at least one cylinder) to see how it reads comparatively to the suspect cylinders.

These engine will run fairly smoothly when one bank of cylinders is completely off-line since they are horizontally opposed but you would barely have enough power to move forward without a lot of throttle applied.

[64von]

The compression tester I was using was junk so I have another and am going to try it this week sometime. No more leakage than I am getting back through the tubes I would say it is normal leakage. I did the pressure test and nothing coming out of the intake or exhaust nothing that you can hear from the crank case/ oil fill . So I think I have eliminated the compression problem and will confirm with a better compression test and if it is good that brings me back around the carb swap. I have good spark on all the cylinders Thanks

[64von]

GOOD EVENING
Good news with a good compression tester compression is good . So I toke the carb apart and blew it all out and set float. It was ok any way.
Now when you put your hand over the carb it makes a difference in the way it idols. the engine pulls down. But I still have a miss under a load.
I am going to the distributer next.