Hi, I have a 350 SBC in my 40 Ford. Lately, I’ve noticed that it skips for a minute after a cold start. I also noticed that the coolant overflow tank was empty and I was seeing what I thought was steam coming from the exhaust. The scary thing is that if you start the engine cold and run it for a minute or so, and you shut it off and remove the radiator cap, the cap blows off due to pressure. I’m assuming that from what I’m seeing, I have a head gasket that’s gone bye-bye. I just bought a cylinder leak down tester, so that’s what I’m looking at next. Anyone got additional suggestions about what else I need to look at?
Well, I think the cap should blow off. That's why they put those levers on some caps, so you can let the steam off. But, it there is now water blowing out with it, you may be real low due to a leak. When ever I had to take the cap off a hot engine, we kept a hand towel handy to wrap around the cap so we didn't get scalded. Sometimes condensation builds up in the exhaust system after it's turned off. That will blow out for a bit. I'd check the oil for a milky color, sign of water in oil, same with water in the rad. Oil and water turn to milk.
I'd use the tester that changes color in the presence of exhaust. This is the cheap HF version, 28 bucks. https://www.harborfreight.com/combustion-leak-detector-64814.html It is a simple, quick easy test and will verify the issue. BTW, it is normal to have some steam coming out of a cold exhaust. Basic chemistry, O2 (air) and HC (gasoline) combine to form H2O (water). If it is a lot and smells like coolant, then it's time to worry.
A Coolant pressure testes to see how much pressure is building up in coolant system,,, Take start up let run, bringing engine to thermostat opening , slowly open cap to release pressure and see if it keeps blowing out ,, maybe air in system , also sign of blown head gasket , cracked head , Cylinder crack) Pull spark slugs to see if any wet with coolant,
steam from the exhaust? stick your finger in the tailpipe? is it wet? touch your finger to your tongue (no this will not kill you) antifreeze is sweet, if it tastes sweet you have a cracked head or blown head gasket
In that pressure in the cooling comes from thermal expansion, if you are seeing pressure in the first minute or so its a fairly safe bet that its combustion gas. As a previous poster said check the smell of the exhaust if its sweet I would do a leak down to try to pin point the cylinder.
It has a skip, like you pulled a plug wire off, but it straightens out after it runs for a couple minutes
No a very small amount of ethylene glycol (anti freeze) is harmless. In the event that you ingest too much antifreeze just drink some ethanol alcohol -Whiskey or whatever your favorite is, ethylene glycols antidote is ethanol alcohol. I tried to talk a boss into keeping a bottle of scotch on hand for just an event He wouldn’t go for it said something about the crew chugging antifreeze shook his head and walked off LOL Everyone should probably keep a bottle of antifreeze antidote in their garage ha ha. Dan
With a pressurized cooling system you can get coolant into the leaking cylinder after shutting the engine off, then that coolant prevents the cylinder from firing for a while after startup. A modern diagnosis for that os an inspection camera going in through the spark plug hole, looking for coolant drops. Another is a pressure sensor or pressure pulse sensor on the coolant system hooked to an oscilloscope, showing the pressure rises every time the problem cylinder is under compression. Add a synchronisation signal from ignition on one cylinder and you can see which cylinder is building pressure in the cooling system.
That ''skip'' you talk about is the faulty (leaking head gasket) cylinder, and when it evens out, is when the coolant has been spat out, and the cylinder fires again.. Time to pull the heads..
Diagnostics will go a long way. The taste test is an easy thing. Pressure checking the coolant system is inexpensive as well. The “skip” and exhaust moisture may or may not be related. I’d not rip it apart just to put it all back together and find out one or both concerns are still there.
The reason the caps blows off after a cold start and a minute of running is because cylinder pressure is getting into the cooling system. Correctly operating cooling systems build pressure because when you heat coolant, it expands, but this does not happen in a minute or two of running. I completely agree with Moriarity, you have a damaged cylinder head gasket, cracked cylinder head, or a cracked cylinder wall. If you don’t see anything obvious upon disassembly, look very closely at the fire rings around each cylinder in the head gaskets for cracks or splits.
With the cap off and running the engine does it have pressure and pushes coolant out of the rad ? how much coolant have you lost over what time frame ? how much steam or smoke is coming out of the exhaust ? as @Moriarity said the smoke and or “liquid “in the exhaust should have a sweet smell or taste. could be head(S) or head gaskets , could also be intake gasket . Pull the plugs and look for “ clean “ plugs what @RodStRace posted is a great tool I got the snap on version and works very well . “ combustion gas sniffer “ All this can be accomplished in less then an hour . Oil that looks “ normal “ is simply an indication the head gasket is not completely fubar , seen more then 1 engine with a blown head gasket doing the James bond smoke screen and the oil was clean clean . could also be a tune up issue , bad gas , or carb issue . All this can be looked at and finding found in about an hour or 2 good luck keep us posted .
if it was the intake gasket he would have coolant in the oil and he said that he does not. honestly the tailpipe taste test takes 10 seconds, then get out the wrenches
It isn't called a skip. It is misfire. Proper terminology can go a long way when describing a problem..... or a lady for that matter.
My buddy years ago had a '65 Belair with a milkshake for oil... really funky stuff. The "oil" and radiator content were one and the same. We were out driving it on a hot summer day when we hear a BANG from under the hood. He pulls over and pops the hood... a milkshake fountain was coming out of the radiator... where is the cap? It did blow off, along with the radiator neck. A day later he drove it into the scrap yard.
Guess it depends on your upbringing. I always heard it called a skip if it was intermittent, or a dead skip if it never fired. Never even heard the term misfire until it started showing up on OBD code readers. We never had the means to check for gasses in the coolant when I was young. Took the radiator cap off and looked for bubbles in the coolant. We have better methods now, you'd be stupid not to take advantage of them, if you doubt what you see. I'd do several checks before I jumped on the headgasket. Good Luck.
Here in central Illinois , as far back as I can remember (1950's) it wasn't a ",skip" or a misfire" , it was simply a "miss" , I.e. " see if you can find the miss in that chev , ford , etc "
In general if I had a "miss" in anything I was driving, I tried to talk her into the back seat.. Good Luck to the OP on finding and fixing his problem.
Just pull the plugs, if there is a cylinder getting coolant in it the plug will be washed clean. Some of these answers are pretty amazing.
I thought the first thing to do was to ,remove the radiator cap , fill the radiator, then with the cap off, start the engine and watch for bubbles.
It has to be a cracked head or a bad head gasket. 1. You’re losing coolant, I assume you checked for leaks externally. 2. Pressure in the radiator after running for a short time. Not enough heat to cause pressure from coolant expansion, almost guarantees a leaky head gasket or cracked head. 3. A miss, skip, misfire may or may not be caused by coolant, several posters suggested pulling plugs, if one or two plugs are cleaner than the rest there’s the problem. 4. Coolant in the exhaust - easy test Could be a gasket or a cracked head bad gaskets are easy to see a cracked head ? May have to take to machine shop. I had a bad head gasket that allowed oil into the coolant but I never saw coolant in the oil . Dan
I’m sticking with “Skip” we always used it as a generic term for a dead hole caused by any think from a bad plug or wire, to valve problems to a hole through a piston. I didn’t get far last night. When I ordered my leak down tester, I figured a low end device would be ok but I may need to modify it to get it to work. It’s a two gauge unit with the second gauge calibrated in %. The drawback of this device is that you need to calibrate it statically to a 0 leaking % position and then test the cylinder. The calibration pressure for 0 % leakage. Is only around 20 PSI, not enough pressure to hear anything. Another thing I didn’t understand was if I removed the tester from the cylinder, allowing maximum air flow, the % of leaking is only about 10 to 15 % meaning even a cylinder with no piston in it would still test as good. What am I missing here guys
A leakdown tester is a good tool, and should have come with instructions. You will need an air compressor that hopefully can be adjusted to 100 PSI. You then need to rotate the cylinder being tested to TDC with both valves closed. Install the hose in the spark plug hole, then connect the air fitting from the compressor. The amount of leak will be shown on the gauge. https://www.motortrend.com/how-to/cylinder-leak-down-test/ It is a bit more involved than the other tool I showed and tests for more issues, but you have symptoms that make you suspect one problem that the other, cheaper tool will find quicker and easier. Whatever the results, you will have to remove at least one head. The leakdown will pinpoint which cylinder (and bank) needs to be done. I'd say that unless the engine is really hard to work on, it would be smart to remove both heads.
I don't disagree, but when you have the ability to figure out what cylinder is leaking before taking anything apart it's a really good idea to do that. If you rip it apart not knowing where the problem is and can't see anything obvious you still have 8 suspect cylinders and 2 suspect heads, you either examine it all very closely until you hopefully find the cause of the leak or just throw new gaskets in it and hope for the best. On the other hand, if you know for sure the problem was cylinder number three you have one cylinder and one quarter of one cylinder head to focus the examination around. Might still not find anything for sure, but at least you know that all those maybes you see around the other 7 cylinders can be more or less ignored. Just like a good lawyer wants to know the answer before asking a question I want to know as much as the engine can tell me before I rip it apart and destroy potentially important clues. Much better to spend a bit more time testing before disassembly, than a higher risk of not being sure if the problem was fixed before putting it all back together again, possibly wasting a bunch of time and the money spent on a gasket set because the leak is still there.
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