Couldn’t say on calibration, but I used a 3/8” drive and another 1/2” drive to confirm. Checked at 85 then again at 90 to see if I could get a little more out of them, got 1/8 turn more. checked bottom radiator hose again today and inside water pump when changing the back plate gasket. I’ll double check top hose, but it filled through radiator and I used the top hose for the valve stem when doing a pressure check. Also still wouldn’t account for combustion fumes in radiator...
Yes, I got all of that babblewon. That's why I said it just don't add up. A very odd series of events.
When I built the 51 that is my avatar I had a water loss issue in it. I built a fresh motor, your basic 400hp SBC. No brainer simple package. Took the stock 51 Rad to my standard shop and had it re cored. While at it I told Bob to change the cap neck so it would use a normal 12 lb cap and put a baffle in the top tank. Picked it up 2 weeks later. I noticed no visible rivets holding the baffle to the tank on the outside. I removed the new cap looked inside and no baffle. Bob convinced me a baffle was not needed put the New cap back on and off I went. Finished the build and ran in the new motor without any heat issues. Over the next weeks I'd drive it 20 miles and the Temp would rise enough to concern me. It never got real hot but lost a fair amount of water. I talked to my builder and we decided it must be a crack in the Exhaust runner siphoning water into and out the exhaust. I didn't want to tear a motor apart over a fresh new paint job, so I decided to just change out the complete motor and use the runner sitting in another project. Instantly had the same issue. Having not yet added Antifreeze there was no color trace on anything. Hot august weather and hot water and it goes away. I was standing with the new Rad Cap in my hand looking at a low water level again when I noticed the receiver neck didn't look new, and there it was. The 51 Ford had gotten away from the old large dia cap and went to the same dia. that became the normal size only it is a 1" deep neck. The cap that is pretty standard is 3/4" deep. I knew that and is why I wanted Bob to change it out. He did not do that along with not installing a baffle. What was happening is I was moving enough water it would come up and spill out the drain tube into the air and dissipate. It never lost enough to get overly hot. Gave me fits for 3 weeks. Was also the last time I used Wilson Radiator. Problems can be very simple and still be overlooked. Also, Assuming someone else does things correctly will get you in trouble for sure. Check, check and check again. It's always the little things.
Does anyone think its possible for the head gasket to allow the high cylinder pressure to escape into the cooling system without the coolant getting too the crankcase?
Right now that’s what I’m thinking. Machine shop told me it is very possible to have gasses escape, but the small amount of water be sucked back by vacuum. Hopefully he gets them pressure tested tomorrow so the heads themselves can be eliminated from the equation.
Cylinder pressure in an internal combustion engine can routinely reach over a thousand PSI so is it possible for combustion gasses to enter the cooling system while coolant would be prevented from ending up in the cylinder?, the answer is yes but the transfer of gasses will always leave some sort of telltale evidence behind, otherwise, how could you figure out what caused the problem? Is it possible that incorrect head bolt length would cause a decrease in clamping force between the block and heads leading to head gasket failure and combustion gasses entering the cooling system? The thermal expansion coefficient for gray cast iron is 5.8, for forged steel, 7.2 so it is possible that improper cylinder head clamping force coupled with thermal expansion could lead to head gasket failure, but once again, not without leaving telltale evidence behind. From the pictures babblewon has shown I see no clear sign of head gasket failure, if the machine shop can't find any cracks in the heads and the head bolts are taken off the table as a possible source of the problem, the only other possibility is a cracked block.
For sure but not for long without an obvious gasket failure. I feel it's been run long enough that should have left a very clear mark.
junkman888 makes a clear description in this line. quote"Cylinder pressure in an internal combustion engine can routinely reach over a thousand PSI so is it possible for combustion gasses to enter the cooling system while coolant would be prevented from ending up in the cylinder". The leakage past may not leave a mark but as long as your Ign is firing the plug that gas leakage will also burn just like the Cyl fuel thus leave a burn trail at the leak point. There's you mark or tell tail. I don't see any of that kind of mark.
Truckedup, years ago, my neighbor Fred had one of those '70s Subaru coups that looked normal from a distance but up close appeared 3/4 scale. When he bought the car it was running on three cylinders so I helped him remove the engine and carry it up on his porch where he did a quick and dirty rebuild finding as the issue a blown head gasket so I know exactly what you are talking about. From that experience I learned; the design of the Subaru engine was greatly influenced by the motorcycles of the time, if not Briggs and Stratton. Two; A head gasket, once blown, does not "un-blow", it stays blown, it does not cure itself and there are always telltale signs of failure. Three; There are only thee sources of combustion gasses in the cooling system; a blown head gasket, a cracked head, a cracked block. The pictures of the head gaskets show no sign of failure, once the cylinder heads are tested and show no cracks, the only possibility left is a cracked block.
Once both heads are on good and tight there won't be any problems . No head or block leak just some undocumented milling on a block is my guess.
I guess the $100 question is why one head was easy to remove also the 1 head gasket doesn't look like fire rings where compressed. Richard holdener takes quite a few Motors apart put some back together and uses the same head gaskets. Maybe he can put the old head gaskets back on torque the head and take it back off and see if the firing is compressed.
Damn! I wish I'd thought of that! Could his head bolts be fatigued to the point where they stretch and won't hold proper torque? Or would they have more likely broken during assembly before reaching torque? Curioser and curioser.
I seem to remember the machinist telling us to use washers on top of the rockers if we were using bolts . And to also to take down the dowl height. He took .010 from the heads and deck surface. My dad handed me a file and told me to think about what the machine shop did ( relating to the dowl pins ). I remember getting nervous and filing the hell out of those things .
Got heads back from machine shop yesterday, they checked out good after pressure test. I did find that on the side that the head slid right off the block during disassembly, the dowel pins were too tall. I measured (caliper tail) the inside of the head where the dowel fits, then took that to the head, the dowel was at equal height. The other side of the motor dowels had probably .040-.050 clearance. I tapped them down and they now have plenty of clearance. I had a funeral yesterday so that’s as far as I got. I’m going to attempt to get out there today and get it assembled.
Ok. So all back together and fired up with radiator cap off and a no spill funnel in it. Lots of air still coming out. Got up to 140 temp and started bubbling pressure out top of radiator again, damnit! Drained a little coolant and ran the combustion gas blue fluid test 3 separate times. No change in color. Seems there is not combustion gasses in the cooling system any longer. decided to put radiator cap on and run it (13psi cap) Ran for 25 minutes, got up to 190 and t-stat opened and temp dropped to about 160. It’s sat and idled like that for another 15 minutes and never got hot and did not purge out the overflow/vent tube. So I decided to take a short drive. drove 10 minutes to a buddy’s and let it idle at his house for about 10-15 minutes without radiator fan on to see if it would get hot. It just sat and idled around 150-160 temp. Upper radiator hose not hard and no steam or coolant out of overflow. drove back home (10 minutes) and backed into garage, started getting hot. Up to 195 and the upper radiator hose was rock solid. No coolant or steam out of overflow and it didn’t blow cap, but I shut it down cause that upper hose was scaring me and the temp was not going down. boiled a pot of water and stuck t-stat in it. Per the thermometer the water was 190 and no movement on t-stat. Ran it under cold water and brought water to to 200 degrees in pot. Lowered t-stat in it and it started to open, but very minimally and very slowly. I’m gonna go grab a high flow 180 t-stat from parts store in a little bit....
Pressure and flow tested radiator. pressure tested block again to 30 psi, found 2 exhaust studs that are leaking coolant...
Swapped thermostats today. Took a little drive through the hills, maybe 20-30 miles. Car ran 150 temp while moving, climbed to 195 while sitting for extended period. Soon as the t-stat opened, back down to 170 at idle and then again 130-140 while moving. Chasing a bad electric temp gauge so I Jerry rigged a mechanical one for reference. It’s looking like I may be out of the woods after replacing the head gasket. Thank you to everyone’s effort and helpful knowledge. Fingers crossed and hopefully I can start fine tuning all the other stuff.
He was saying that the leaking exhaust studs were missed during the testing. And unless the heads get to 160 degrees they probably don't leak ( as those of us who didn't comment understand ). These engines are the probably the most well built to ever leave Detroit. For all of the failures and " weak points " you read about these , make no mistake that it takes A LOT to mess one of these up. Overheating isn't warping these heads. They run for quite some time with no cooling whatsoever ( dragsters ). The blocks are not as strong as the RB blocks that replaced them but they are a close second. As long as they have oil to the the top these engines are happy. And while I'm typing ... the 413 or 426 W never did run as well as a 392 ( and the fact that the 426 hemi came to be proves this ). All of the fancy manifolds and tens of thousands of man hours couldn't make it so. Why the early hemi was discontinued so abruptly makes no sense. Even the drawings for the engine were gone by 1963 ( Tom Hoover ).
The Jalopy Journal
