I have been battling a potential internal coolant leak over the past couple weeks. Loosing/low level coolant in reservoir after a couple runs, no visible external leaks, a bit of white smoke on start up, rough idling to the point of almost stalling out and hard start up. Hooked up a pressure gauge on the radiator this morning and losing pressure with no visible leak. Currently removing spart plugs and checking cylinders with a borescope. I did recently remove one of my headers to weld an exhaust leak near the flange last week and noticed that coolant was leaking out of these two header bolt holes immediately. What's up with that???
LA 360 Internal Coolant Leak
- Thread starter Mcfarlrm
- Start date
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All 4 corners of the exhaust go into a water jacket and they need to be sealed. The factory uses studs.
Good to know. Saw a bunch silicone too when removing. I assume whoever owned it before be used silicone to seal. Really hoping that my issue is a head gasket at this point.
Did you have this problem before you removed the header to work on it?
Yes, was loosing coolant prior. However, it has been getting substantially worse the past several days. Yesterday it struggled to fire up a bit on cold start (in FL so warm weather) and then stalled out on me about a minute into idle. Tried restarting and it would not fire up after numerous attempts. May have flooded it at that point so waiting until this morning to try again. This morning struggled to get it started and had pedal to floor to clear out. Probably the hardest start I've ever had the past four months of ownership. Had to keep RPM's up to keep it from stalling out on me, which took a good few minutes to get it idling at an acceptable rate and noticed white smoke form exhaust, which cleared after a few seconds. Took it out for a drive and it wanted to stall out on me at every stop. I did adjust the idle on the carb, which helped a bit.
That probably isn't the cause if your rough running. A head gasket may steam like a Stanley and if it loads enough coolant in a cylinder it might hydraulic lock and could cause damage.
I left the coolant pressure tester for a good while and coolant level did not seem to go down even though the tester was losing pressure every time. I pulled my newly installed plugs and they are black. Doing a compression test now. Also, going to attempt to bypass the old MSD box to see if that may be causing an issue. I've heard some bad things about those boxes causing intermittent issues.
If your spark plugs are black I would assume you're having a carburetor problem also.
Brand new carb as well and had a neighbor who races stock cars and owned a couple 360's in the recent past help adjust everything. Funny thing is when we adjusted the idle mixture screws, it really didn't seem to do much of anything either which way.
Professor Fate
Push the button, Max...
How does the oil look? Look for moisture in the cylinders, but at this point, trying to check with a borescope is just dancing around the problem. You're gonna have to crack that puppy open regardless of what you think you may see. And the sooner the better, as TMM stated.
Bad gasket: gotta open it up.
Cracked head/cylinder: gotta open it up.
Get actual eyeballs on the problem. Pay close attention to the front of #1 cylinder bore with the piston at BDC.
Bad gasket: gotta open it up.
Cracked head/cylinder: gotta open it up.
Get actual eyeballs on the problem. Pay close attention to the front of #1 cylinder bore with the piston at BDC.
Some other areas to check when you pressurize the cooling system that were not already mentioned above already
- 4 corners of the intake where head meets intake there are cooling passages in the corners
- Front timing cover and Water pump. Some of the bolts hit water and need to be sealed. Leak could also be around the water pump if you did not look there.
- Frost plugs on the head and block. Two of the frost plugs are on the back of the engine which are covered by the bolted on trans. Look for leaks or bubbles around the visible ones when pressurized.
- Thermostat (I assume you looked at this
- Any of your hoses and their connections
- Heater core inside the car.
- A crack in a head or block
- Check your oil for water as mention in the prior response. Any whitish froth in the breather caps, dipstick or under the valve covers? If yes could be coming from a few of these and the above mentioned items.
Good luck. I have had to chase these before.
- 4 corners of the intake where head meets intake there are cooling passages in the corners
- Front timing cover and Water pump. Some of the bolts hit water and need to be sealed. Leak could also be around the water pump if you did not look there.
- Frost plugs on the head and block. Two of the frost plugs are on the back of the engine which are covered by the bolted on trans. Look for leaks or bubbles around the visible ones when pressurized.
- Thermostat (I assume you looked at this
- Any of your hoses and their connections
- Heater core inside the car.
- A crack in a head or block
- Check your oil for water as mention in the prior response. Any whitish froth in the breather caps, dipstick or under the valve covers? If yes could be coming from a few of these and the above mentioned items.
Good luck. I have had to chase these before.
Well if your idle mixture screws are not having much effect that right there tells you something is wrong with that new carburetor.
Compression on all cylinders was good and cleaned the plugs. Fired right up no issues whatsoever and let it run in idle. Idled great until I put it in gear, RPM's shot down and a split second later a loud pop from the carb and died on me. Did this about 4 times before I called it quits for the day.
If one (or more) cylinder(s) has a piston top that looks like it was steam cleaned you likely found your bad head gasket.
Let me guess: Holley carb or clone.....
White smoke & losing coolant: will be an internal coolant leak that can be hard to find. Compression test may not reveal anything. Can also be heat related, such as a crack in the bore that gets bigger when the engine heats up; crack/pinhole in intake port or combustion chamber; blown head gasket. Etc.
White smoke & losing coolant: will be an internal coolant leak that can be hard to find. Compression test may not reveal anything. Can also be heat related, such as a crack in the bore that gets bigger when the engine heats up; crack/pinhole in intake port or combustion chamber; blown head gasket. Etc.
The carburetor needs further tuning for sure.
Also worthy of note. The four corner studs Mike referred to are almost impossible to get the leaks completely stopped with bolts. People often think they've done it, but most times they still seep very slowly, even when sealant is used. The reason is because the correct studs have a bevel that when the studs are tightened into the head mates against a female bevel in the stud hole in the head and effectively seals the stud. That's why it's so difficult to get a bolt to seal there because of that female bevel in the head. Although it does sound from your symptoms that you might have a leak into the combustion chambers somehow.
Just remember new ain't the same as good and stock car racing ain't a street car.
Edelbrock AVS2 650. Tearing everything apart next week. Checking valve assembly, head gaskets, heads, cylinders, etc. Only real way to see what's going on at this point. What has be scratching my head is that after the compression test, coolant pressure test and cleaning and spacing the spark plugs, it fired right up and idled like a champ after several startups. However, as soon as I put it in gear the RPM's dropped substantially, carb popped and died. This happened every single time putting it in gear.
After much thought about the problem I have come to the conclusion that the car is constipated. Possibly somehow it is getting Lasix so therefore it's dribbling because it can't take a full whiz. This is not a professional opinion it's just a possible conclusion.
After some timing adjust and carb tuning she is running like a champ. Going to run it a few more times to see how it holds up. I think I may have been losing/evaporating coolant through the radiator cap and currently waiting on the replacement.
Haha, just like I said the car was constipated.
My pocket book and free time are currently thanking me. I was on the verge of tearing everything apart this week.
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