I have an issue with the 327 in my coupe. Once the car is warmed up then at low idle I get a snap or pop or clicking somewhere in the cooling system. I notice that the upper radiator hose is giggling and something is going on. This has been an ongoing problem for quite sometime but I have finally had enough and would like to get the problem solved. Does this ring a bell with anyone. I think I have replaced the 180 thermostat to no avail. Thanks for any help!
I would check for hydrocarbons in the coolant, sounds like a head gasket issue. If you don't have either a gas analyzer or the liquid block test stuff, motor over to a shop that does. With the engine running and rad cap off, hold the sniffer hose as close to the coolant as possible. Anything over 6 ppm HC is bad.
Yep, you've got Rice Crispies in your cooling system. Apparently, your upper radiator hose thinks it's funny. Sorry, I guess I'm feeling like a smart ass today.
Sounds about spot on, somewhere there is exhaust leaking into your cooling system. Any decent radiator shop can check for it. Doc.
A sticky or stuck thermostat will make some hellacious noises. Sounds like a small guy swinging a huge hammer inside your radiator/intake manifold. Just for giggles and grins, pull the Tstat out and see if the noise goes away. Much cheaper than buying parts you may not need.
Thanks Guys, I'm going to pull the thermostat this weekend and if that doesn't do it I'll look into it further as suggested. Why is it that I can always find everything except what I'm looking for??
If it's in that coupe I'd be tempted to come out there and do a head job just for pictures of me working on that car, and maybe a place to stay cause that is quite the drive. Good luck any how, sounds like a head gasket to me too though. Unless you let a massive amount of air into the block and it has a hot pocket that hasn't bled out? But I don't imagine that would last too long.
An update if it might be of any help. I ran the engine without the radiator cap and as soon as the engine warmed up it started spewing out coolant. I have wondered about an air pocket but uncertain how to bleed out the system. The heater hoses run above the engine through the firewall, wonder if that might be an issue? Still plan to pull the T-stat this weekend. I have been sorting out some issues with the fuel system and timing wondering if I might have a problem there. The car runs great but still has a slight hesitation (sputters) right off idle. Thanks!!
You might consider installing a Flush Tee (Like Prestones' Flush 'N Fill) in a heater hose as high-up as you can. Pull the little cap on the Tee and fill with coolant until some comes out. That will effectively bleed the air out of the system. With it, you might also consider flushing the heater core, it may be filled with crud and causing the restriction.
Pretty typical symptom of coolant violently boiling inside the engine and creating pockets of steam that force out the coolant. It is those surges that are making your noise.
Thank You sir and hate to sound stupid, but if what you say is correct what is my next step? Something else maybe worth mentioning is this car never overheats. It barely reaches 180 degrees w/ the Ac on.
I've seen cars with freshly filled cooling systems make snapping and popping noises from the cooling system as they are warming up and have air pockets. Shut them off for a few minutes and they generally suck in the remaining needed coolant and problem is gone. This doesn't sound like your problem since it seems yours is more long term, but I wanted to mention it in case anybody runs into it. Devin
Make sure you have your thermostat bypass installed and not blocked off Make sure the thermostat is opening and closing correctly by removing it from the car and putting it in a pot of water on your stove. Use a cooking thermometer to measure the temp and observe the action of the stat.
I had bad air pockets in my cooling system drive you car up on ramps run it with out the radiator cap and it will start burping the air out
On sbc I always drill a small (1/8") hole in the thermostat to let trapped air through when it's closed. Also is the radiator a modified stock one, what type of pressure can it handle, if the cap pressure is too high you'll hear the tanks expanding and contracting. I had a 7 psi cap on the flathead and you could hear it "pop" and I went to a 0 psi cap and it went away. also when re-filling jack the front end up and use one of these to get all the air out.
Finally someone else with the same problem I had. My brand new Smeding cate motor, Walker radiator, new water pump t-stat etc, same noise. I tried multiple t-stats. I had drained and filled my cooling system several times while completing my car, not always on purpose.I think it was trapped air. Mine eventuall stopped doing it.Sounds like trapped air to me.But I'm not an expert.
I think you can get them at kragen/o'riley now, I bought mine on the tool truck years ago. it's a Lisle 24610 toolwarehouse.net 19.90 summit has them for 19.99 amazon has them for 25.23
As it turned out my bypass was not connected. I made up this T out of copper pipe fittings. It seemed to help but the issue seems to remain. I am going to get back on it one of these days but don't drive the car that much and have moved on to other things. I will try raising the car in the front and removing the radiator cap while running. If that doesn't do it I'll try flush kit. I think I have one of those around somewhere?
@banginona40 Did you ever get this problem resolved? I have a SBC 350 with a new radiator and it has the same problem. Any help would be appreciated. Thanks!
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