VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Losing my cool(ant)

I recently rebuilt the stock 216 engine in my 1940 1/2 ton pickup. The rebuild consisted of bore/hone cylinders from standard size to .020" over; new OEM cast iron pin-fitted pistons w/new .020" over rings; reground valve seats; new valve guides and new valves; new cam bearings; re-surface (deck) the cylinder head; adjust rod and main bearing clearances. The machine work was done by an engine shop, but I did all the re-assembly myself (I had done three 216 motors previously so I felt confident that I knew what I was doing).

After reassembly/re-install, the engine started right up and sounded good. I proceeded to break the engine in by driving it a varying speeds, but not over 45 mph for the first 300 miles, changing the oil at 200 miles. After the first 300 miles, I began driving at 50 to 55 mph (2500 to 2700 rpm), and now have about 2500 miles on the engine, most of it at 50-55 mph.

After 2000 miles, I ran a compression test with the following results:

#1 dry 110 psi; w/oil added 140 psi
#2 dry 98 psi; w/oil added 125 psi
#3 dry 101 psi; w/oil added 120 psi
#4 dry 102 psi; w/oil added 130 psi
#5 dry 98 psi; w/oil added 125 psi
#6 dry 111 psi; w/oil added 140 psi

While I'd like to see them all at 110 psi or better, the readings are not that bad, though the significant difference between the dry and oil-added readings would indicate that the rings have not seated fully.

The engine runs strong and quiet, but I am getting a fair amount of oil smoke from the exhaust, though the actual oil loss rate is not that high--perhaps 1 quart per 1000 miles.

Here's the problem: I'm losing coolant out the overflow tube. I put a bottle under the overflow tube so I could see how much I was losing, and it varies, but looks to be about a quart in 30 miles at 50 mph. The coolant loss is not from boiling, as the engine temp never went above 180. The loss is not from over-filling, as I started with the coolant level just above the top of the core with the engine hot. It appears that the coolant loss only occurs while the engine is running.

So, I'm guessing (hoping) I have a leaking head gasket, though I suppose it could be a cracked head or block.

Does anyone have any other ideas about what the problem may be?

Mark

Do you have milky looking engine oil?

Bad radiator cap? Could be the caps seal. What pressure cap do you have on it? I changed from a 0 pressure cap to a 4 lb. cap and it took care of my spitting up and overflow. Might be a solution...Worth trying. Good Luck!

Mark,

Like you noted, the head gasket or a crack could be the culprit. Easy to check. Just trip the fan belt, ease out the thermostat, replace the housing, fill to level (at the top of the housing) and crank 'er up. Any compression leakage by the head gasket or through a crack will be noted by either a trickle of bubbles (usually/generally a crack) or a gush of water (usually a head gasket).

Only, other thing I can think of is that the radiator is stopped up enough to cause the water to back up in the top tank to back up and, in turn, and overflow whilst driving along at 55 or so.

I'm assuming you have good bottom hose(s) and that the torque to the head bolts were right on and the bolts were not bottoming out before you reached proper pressure to the head. Also, that you used proper sequence in tightening the head bolts.

Hint on seating the rings: Put a reasonably heavy load in the bed (or pull a loaded trailer) and drive for about fifty to a hundred miles at 55-60 mph. If the engine is right in all other respects, you're not gonna hurt anything. Others may disagree.

Good luck with it. I used to assembly my own, also. The machine shop, however, started warranting the engine for 12 months or 12K, if they assembled it. Sounded like a deal to me.

You shouldn't need a pressure cap. Using one would only help mask the symptom not fix the cause of the problem.

Charlie

I may not be the one to listen to on breaking an engine in but I'll go ahead and say my two cents. I've broken in several airplane motors which are just like car motors. After we let an engine test run for 1 to 2 hours, we then fly it like we stole it for an hour....that's pretty much full throttle and fly it hard. That's how we get the rings to seat properly. The first 1 to 2 hours on the ground gets all the parts lubricated properly and gets everything in place. Then, by flying it like we stole it seats everything properly. Keep in mind....we're doing this procedure on a $25,000 motor and we've not blown one up yet.

As for losing coolant: The radiator cap on those models were not pressure caps. I'd check the color and texture of the antifreeze and the oil. If it all looks completely normal, it's gotta be coming out of the overflow for some reason. I'd be willing to explore the idea that the radiator is not allowing the fluid to pass properly.

I think I was dealing with two separate problems. Just before I installed the catch bottle on the radiator overflow tube, I had installed a water pump that I rebuilt in order to road-test it for use as a spare. I noticed that when I finished assembling the water pump on the bench, there was no resistance to rotating the fan pulley. Normally, on a newly rebuilt pump, there will be some resistance to rotation due to the friction of the rotating seal face rubbing against the stationary face. I was afraid the seal might leak, but I installed the pump anyway. On startup, the pump did not leak, so I headed out for the road test that I referred to yesterday that resulted in coolant overflowing from the radiator.

I got to wondering if perhaps the water pump was sucking air in through the seal and aerating the coolant in the system. That would explain the higher than normal coolant temperature that I was seeing, as aerated coolant doesen't absorb heat from the engine as well as non-aerated coolant. It would also explain the coolant "fluffing up" and overflowing.

To check it out, this morning, with the cooling system full, I started the engine and let it run at about 1500 rpm. After about 15 minutes, with the radiator cap off, I could see the coolant level beginning to rise. I put the cap back on and the coolant began overflowing into the catch bottle. It was clear that the coolant was full of air bubbles.

So, I shut the engine down and let it cool for a while, then removed the rebuilt water pump and installed the original pump. After refilling the system, I took the truck for a 40-mile road test at 60 mph, during which I noticed the engine temperature was running cooler than it had the day before. When I got back home, there was no coolant in the catch bottle. That pretty well convinced me that the "rebuilt" water pump was the culprit with respect to the coolant overflowing.

However, while there was no coolant in the overflow bottle, the level in the cooling system was down well below the top of the core, so I'm still losing coolant, and since it's not coming out the overflow, it has to be going into the engine.

Clinging to the hope that it's a head gasket problem, I guess any given cylinder is under vacuum on its intake stroke, at which time the coolant could enter the cylinder via the gasket defect, where some of it would be boiled off and exhausted during the power and exhaust strokes, and some might be blown back into the cooling system through the defective gasket where it entered.

As a further piece of evidence, I notice that after the engine has been run and thoroughly warmed up, after shutting it down for a half hour or so, on re-starting, I get a huge cloud of "smoke" from the tailpipe. I was thinking it was oil smoke, but now I'm thinking it may be steam from vaporized coolant that collected in the engine while it was idle.

I guess the next step is to pull the head and have a look.

Mark

You can get a test kit to see if you have combustion gases in the cooling system. This is a positive test to confirm what your coming up with.
http://www.autobarn.net/licoledefl.html

Don

If you pull the plugs you may find that one looks different then the others. When I had coolant passing through a combustion chamber it left residue on the plug.

Don,

I thought I remembered seeing some mention of a test kit to indicate combustion gas in the cooling system. Thanks for the link.

The info I posted yesterday about my water pump sucking air in through the seal was bogus. The reason there was no coolant in the overflow bottle after I changed water pumps is that the hose on the overflow tube wasn't inserted into the bottle. I noticed that today, so I refilled the cooling system and re-inserted the overflow hose into the bottle and did another road test. After 10 miles, the bottle was full, so the other water pump is exonerated. I'm not sure there would ever be negative pressure around the water pump seal on these pumps unless the radiator was badly plugged up or the pump inlet hose collapsed.

Continued testing on my cooling system showed that if I catch all the coolant that overflows and poor it back into the radiator, the coolant level comes right back to where I started, which would indicate that no coolant is being lost into the engine.

As for the "smoke" from the tailpipe, alas, I'm afraid it is oil smoke. I guess I can't make any more excuses, and I'll have to open the motor up and see what's going on in there.

Mark

Mark
You may well be right about a partially blocked radiator causing the coolant displacement.
With the smoke a general rule is blue smoke indicates oil, white smoke (steam) indicates water (may only be very humid intake air) and black smoke indicates excess fuel.
Tony

I purchased a universal coolant expansion tank and installed it in a bout an hour. It is designed to take the hot overflow and then as cooling occurs the coolant is returned into the system. A $38.00 investment and a bit of time solved the problem. The tank came with instructions and the mounting hardware.
Normbc9

I suspected a leaking head gasket as the cause of my coolant overfow, as thermal expansion was definitely not an issue. I replaced the head gasket and my problem was solved.

I don't know why the original head gasket started leaking. It was a high-quality copper/composition gasket made my Best Gasket (included in The Filling Station overhaul gasket set), and it only had about 2,000 miles on it. I had had the head re-surfaced, but not the block, which looked good. I installed the gasket with Copper Seal spray-on adhesive, and I re-torqued the head bolts to 85 ft.-lb. after thoroughly warming up the engine. There was no obvious evidence of leakage when I removed the head, so I couln't tell exactly where it was leaking.

Anyway, I replaced the gasket with a new one of the same brand. All the holes in the head/block are symetrical from end-to-end, so it is possible to install the gasket with either side up. One side of the gasket has a rolled edge around each combustion chamber opening. On the original gasket, I installed the rolled edge down, but on the replacement gasket I installed it with the rolled edge up. Apparently OEM gaskets were stamped with "This Side Up" on the side with the rolled edge, but my replacement gasket was not marked. Perhaps having the gasket upside down was the cause of my leakage. Anyway, so far, after about 300 miles, there has been no more overflow from the radiator, and the coolant level is staying steady, as it should.

While the head was off, I installed 12 valve stem seals. The seals are evidently for the 289/302 Ford V8 engine. They fit over a 9/16" guide and are for a valve stem diameter of .343, which is what the 216 has. I got them off the shelf for $1.00 each at a local engine rebuilder's shop. I had to cut about 3/32" off the top of the intake valve guides so that the upper spring seat would not hit the stem seal when the valve is fully opened. I used a Dremmel tool with a cutoff wheel to cut the guides so I didn't have to remove them to shorten them up. The addition of the stem seals appears to have cured my excessive smoke on re-start problem caused by oil leaking down the valve guides. Thanks for the tip, Gene.

Mark

Mark, thanks for this bit of valve guide seal information...And good luck with your new gasket, not that you'll need it...! Kevin

I had pretty much the same problem with both my 36 and 37 . It didn't get hot and lose coolant, it lost coolant then got hot. And yes, it was coming out of the overflow tube. Did all the same worrying you did about leaking head gasket, air induction through water pump, etc. Finally pulled the radiator and found the baffel that is supposed to direct coolant away from the center inlet pipe and distribute it across the top if the core had broken loose allowing coolant to impinge on the radiator cap, and in turn go down the overflow tube. Replaced the baffel and in both cases the problem went away.

Correction: I didn't use a Dremmel tool to cut off the intake valve guides--I used an air-operated die grinder with a cutoff wheel. With a Dremmel tool, I'd still be cutting, a week later.

Mark

Mark,

Oh, thanks a lot for the timely correction on the Dremmel.

I slap wore all my discs and melted the unit and my neighbors, as well, a-grinding away with little results. I stopped and was going to ask you about your process but now see that you didn't use one after all.

The way I figure it you owe me a drill and a bunch of discs. Do too!

Thanks a heap,
Charlie

Charlie,

I'm sorry I didn't catch that mistake before I submitted that post. I always read through my posts about 10 times before submitting them, but overlooked that mistake.

When you're done cutting the guides, be sure and thoroughly flush all that gritty grinding detritus from the guide bores and from the entire top of the cylinder head--you don't want any of that stuff circulating in your oil system once you get the engine running.

Also, be sure to break the corner of the inside and outside of the top of the guides where you've cut them off. A light application of an 82 degree countersink in an electric drill will work well for breaking the edge of the guide bore. A small file can be used to break the outside corner--this is important so that the seal will slide on over the guide without damaging the seal.

Before final assembly of the valves and springs, you should check that you have adequate clearance between the upper spring seat and the newly-installed valve stem seal. Insert the valve into the guide, then, leaving the valve spring off, slide the upper spring seat down over the valve stem, then put the keepers in position on the valve stem and move the upper spring seat up into its normal position over the keepers. With the valve, upper spring seat and keepers thus assembled, hold the valve in the closed position and measure the distance between the top of the stem seal and the upper spring seat. That distance must be slightly greater than the valve lift. The valve lift can be found in the Chevrolet Specifications for the model year of your engine. For example, for the 1940 216 engine, the exhaust valve lift is .3118" and the intake valve lift is .2947". The Chevrolet Specifications are available on the oldcarmanualproject.com web site. You actually need to do this step before you cut any guides in order to know how much, if any, you need to cut from the guide.

I should add a disclaimer here. This is the first time I've done this job, and there is one area that concerns me. The new stem seals are held onto the guides only by friction. I don't know if the engines for which these stem seals are intended have grooves in the valve guide O.D's to engage the ribs in the bore of the seal in order to effect a more positive lock of the seal onto the guide. Anyway, I just checked mine, and, after 500 miles in service, all the seals are still in place.

Mark

I was trying to picture cutting valve guides off with a Dremmel and I was thinking.....there are people with a lot more patience than I have!