I need some help diagnosing a leak on my nailhead. Here's what I found today when running it for the first time since April: Before starting it, I raised it high enought to get under to look for any obvious signs of leakage, but found none on the block, lower rad, or rad hoses. There were a couple of damp spots, but I could not tell what caused them. Next I had to add 6 quarts of coolant, just to bring the level about 1/2 way up the rad. I chose not to fill copmpletely, in case it leaks all over my garage floor. Then I ran the engine, with the rad cap off, for about 15-20 minutes. So far, so good, so I put the rad cap back on. Went for a short drive around my block, but no leakage. Parked in my driveway, shut it down, and still no leakage. Next, I looked carefully around the thermostat area, plus the water crossover, and found evidence of previous leaks on top of the timing cover, directly under the thermostat. Looking closer at the bottom of the timing cover, it appears that coolant has seeped around it, and dripped from its underside. Two winters ago, most of the coolant seeped out during the winter but I could not isolate the source. Questions: Just exactly how does the nailhead thermostat system work?? Somebody once told me that it seals both on top, and underneath the water crossover.o No: Could this be the leak source?? What about the timing cover itself, how likely is that to leak?? I believe it's the original one. What about the rad cap?? When the engine was cooling down, I heard a sort of "farting" sound, with an accompanying slight vibration of the rad cap. Could the cap be bad?? Lastly, the engine has always previously run at 190 F in any weather. It has never overheated when the rad was full. The car has an aftermarket gauge installed by the former owner. Any ideas would be appreciated. Thanks in advance.
Most importantly....if coolant is disappearing, keep a close watch on the oil level to make sure coolant isn't leaking into the crankcase! Timing covers can corrode to the point that coolant can leak into the timing chain area, or to the outside of the engine. Coolant flows from the water pump thru passages in the timing cover into the front of the block. It flows rearward around the cylinders, then thru the large block/head water passage in the rear. It then flows foreward thru the heads and into the water crossover, and back to the water pump. When the thermostat opens, it'll (also) flow thru the rad and then back to the pump. There is an o-ring between the water crossover and timing cover....it could be leaking there. You'll have the remove the crossover, and replace the end gaskets AND o-ring to fix that. Hope this helps...and please check your oil for water! (just in case)
Walt, thanks for the detailed explanation.:TU: :beer I'm 99.732% certain that no coolant has found its way into the crankcase, as I did check for that several weeks ago, but I will check it again in the morning. Now just how available are those crossover gaskets and O-ring??Might as well change the thermostat while I'm at it. Any other "while I'm at its" that I should do? I've never owned a nailhead before this one.
I do not have any coolant in the crankcase, so it's off to my local parts store to see they have what I need.ray: Very few nailheads around here.
ck with napa.... they seem to have some nailhead knowledge....Yes the timing cover can corrode and leak....If it leakes to the inside, like Walt said, it will dump coolant into the oil system.... if to the outside, you can see that... Now if the head gaskets are corroded and leaking you cant see that because it will leak into the cyl as the engine is running and go out the exhaust system as steam..... pull the spark plugs and look for one that is white, chalky looking... and the top of the piston will be white chalky looking... if you find one ... run a compression test or get a rad shop to put a ''sniffer'' test on the cooling system to see if there is combustion gas getting into the system... I suspect that you have a head gasket that has corroded, started leaking, allowing combustion gas to enter the cooling system,,,, this will make an engine run hot very quickly and no amount of fixing will cure it....except pulling the heads and putting new gaskets....
Fel-Pro lists #11379 for the water manifold, and #10672 for the water pump o-ring. Core plugs (freeze plugs) can also rust thru after time, and the worst case would be a cracked block. They like to crack just below the core plugs on the side of the block....that can happen if the coolant/water freezes. Either case would produce obvious signs of leakage tho. Have you inspected the heater core or hose connection at the firewall? Good luck, and hope it's an easy fix:TU:
I had this same problem not too long ago, had a leak and couldn't find it. Every time I would get back from a cruise there would be coolant on top of my trans cooler and the coolant level would be a little lower. Eventually I found a couple (3-4) small pin holes in the top radiator tank. Doesn't sound like that's your problem, but it's just a suggestion. Also, I found my leak by pressurizing the system and squeezing the top hose. It started shooting out where my leak was. Good luck!
Thanks for the ideas, please keep them coming!! I picked up a 160 thermostat and gasket, since I recall reading a previous thread that nailheads prefer cooler temps. The thermostat gasket package states AMC, Jeep, and some Chrysler products from 1933-74. The engine currently runs at a consistent 190, according to the temp gauge, which appears accurate. Heater core was replaced just before I got the car, floor pans are dry, no carpet in car right now. It's a factory AC car, with no leaks at the firewall. Yesterday I checked for bad core plugs/cracked block, and they all look good. This morning however, I checked underneath, and found a small coolant deposit directly beneath the passenger side of the block.:ball: There was also a small deposit under the driver side directly beneath the water manifold O-ring and the timing cover and lower water pump outlet. There is some dampness below the O-ring area, on top of the timing cover. This looks to be more involved than I originally thought.ou: ou: Could be that the engine will need to come out if it's a core/frost plug. I do not fully understand just exactly how the water pump O-ring interacts with the water manifold. Is there a direct connection between the two, like a bypass hose system on other engines?? Anyway, I'm heading on the road later this afternoon, so I'll have to dig a bit deeper when I return. Please post any other thoughts you might have, as I really want to drive it some this fall. Thanks again.:beer
If I have it right, ALL the water circulating thru the block and heads returns thru the water manifold and back to the water pump...UNTIL the thermostat opens....then it goes thru the top hose , thru the rad, and returns via the lower rad hose. The 'water-pump o-ring' is what Fel-Pro calls it. It's actually a o-ring for the water manifold, where it fits into the top of the front cover. If the Fel-Pro #10672 number can't be found, look for a #2-313 o-ring from a hardware or plumbing supply store. It's 3/16" dia, and 0.662" ID. Hopefully, that'll do the trick! Last resort is to add some fluorescent dye to the coolant, so you can find the leak by viewing with a black light.
Worst case, take it to Dan at Canada Auto (Route 90 and St. Matthews) and tell him I sent you...that may save you some time, but not any dollars...they do very good work, but do charge somewhat accordingly. I have a couple cars there right now getting safety inspections...sigh.
Sounds like that O ring might be the problem; also check your waterpump for any snapped bolts. They used two different types of bolts, the larger ones went into the jackets and hold the timing case on, and the smaller ones went into the timing cover. These small bolts have an alarming tendancy to snap off when the pump is being changed out, and as a result, leak. Hardly anyone ever really pays attention to them, they just goo up the gasket and hope it holds. (It usually doesn't over time) Centrifugal pumps like to be sealed up all the time, so if there's anywhere it can suck air, it won't work right, creating other problems. Hope this helps...
To keep you all advised, I just returned from my latest 11 day tour earlier today, and will try to get the parts needed tomorrow. Thanks for the tip Derek, if things gets to that point, I'll give them a call.:TU: It'll probably be later this week before I get into this leak again.ou:
Well, I went to my local Napa store earlier today, only to discover that they not only don't stock what I need, those parts are not even available in Canada.:eek2: They did, however, call back to advise me that they would glady special order them in for, get this, about a $40.00 shipping charge.:shock: :shock: That's for something like $10.00 worth of parts.:af: I erred in a previous post in stating that I had the 11379 water manifold gaskets. I actually have the thermostat, and the thermostat gasket. I still need 2 water manifold gaskets, Fel-Pro #11379, which crosses to a Victor # C17961, and the #10672 O-ring, which is Victor # C45257. Looks like I'm going to hit some parts stores next time I'm in America.ou: Oh well, I suppose that I can amuse myself with quick trips around my part of suburbia without overheating it. (It's a small bay I live on).:laugh:
It's just a standard o-ring, not a custom-made-fits-only-old-buicks-specialty part!:grin: Autozone has the water crossover gaskets. For some reason they list them as 'water pump' gaskets http://www.autozone.com/Ntt,11379/s...m;jsessionid=8E2519D1593D756015627A6293F9E3EE If you can't get the gaskets, just make them. The Fel-pro's are 0.050" thick uncompressed.
I can feel your pain when it comes to ordering Buick specific parts in Canada. I've been having "fun" for years! Usually I get a blank stare from the teen-age moron behind the counter when I ask for any Buick 401 parts. The usual answer:"Is that the like a Chevy 350?" Then they give a part that's completely wrong, because the original number has been changed "up" so many times it no longer is the right thing anymore. Just last week I went in looking for plugs to my '46 Super; good thing I had a modern cross-over number for them. The kid behind the counter insisted on a year and model of the car, and then insisted that that car didn't take plugs because it wasn't listed on his computer. You're better off biting the bullet and ordering everything from the US; they at least know what you're talking about. And yes, Canada Customs takes more than their fair share for parts that haven't been available in Canada since 1976. Good luck!
I figured that the O-ring hunt would be a real nice quest.:laugh: I also thought of just making the gaskets, but again, the hunt is sometimes part of the thrill.:TU: I will "get in the 'Zone" later today.:beer Marc, I know what you mean about Canada Customs, but I travel south a great deal, so it's easier for me to just bring small things back in person.
