I asked this question a few months ago,still has the same coolant loss.I have a 305 in my 64 El Camino that uses about a cup of coolant every 1000 miles.This may seem minor,but it's going somwhere.The engine is a 90 305 factory roller block with older #416 305 heads.I picked up the dissasembled engine at cost from a local reptuable machine shop after a previous customer didn't pay for the work.The engine parts where all Magged and pressure checked before I assembled the engine.After about 800 miles I pulled the heads to have them pressure checked again,no problems found.Tests show no coolant in the oil,no combustion residue in the cooling system,no external leaks to be found despite many careful looks at the engine.The heater core is dry as it the raditator and all hoses.This engine has an overflow recovery tank.Everything is new brand name suff,hoses,radiator cap,radiator itself. The engine runs great, 180 degrees at all times.There is no excessive water vapor from the exhaust or any coolant odor.However,one in awhile I think I might smell a faint anitfreeze odor while driving.Passangers don't smell it,just me so I might be parinoid.
You might check the heater core for a leak. A cup every 1000 miles could be pretty hard to find. Larry T
If it's leaking near the exhaust or into a cylinder then it is evaporating before you can find the source. Thus you may never know. My daily driver is the same, 305 also, I just add more coolant. Have you checked the freeze plugs?
my 96 T-bird is doing the same thing, I gave up on trying to find it and just replace the coolant. mine will lose a little more then that..
If the car has factory AC/heat its possible the heater core has a seep and it will drain out the AC drain tube and may be why your smelling it. I suggest you pressure test the system to 21 pounds and let it sit. If it has a leak any where it will show on the pressure gauge.
Could be sucking in through the intake...not all that uncommon on later small block Chevy motors......
Find a shop with a radiator pressure tester. Pump it up to 15 lbs and watch the needle. This will test everything in the cooling system including head gaskets etc. If it holds pressure for a 1/2 hour or so, don't sweat it. I don't know how you could even notice a "cup" in a 1000 miles. Even a tiny leak will show up on the pressure gauge. If the gauge holds, quit checking it for 4000 miles and then add a quart.
Check ALL the hose connections and clamps to make sure they are tight. I had a connection on a hose on the htr core that seeped and it ran in the hole under the carpet. Didn't know I had a leak till it soaked the floor. A hose connection can leak going down the road and not sitting still, cold, hot, vice versa. Weird sometimes. Lippy
Go to the local napa store and they have cooant dye,add to system and run ,put black light on areas and look for leak
My friends water pump was bypassing a drop out the weep hole every few miles, the drop would drip straight down onto the hot lower radiator hose..poof...gone, no smell, no evidence...the perfect crime! I just got lucky and noticed it when it dripped.
A "cup" is not much. If you go 2000 miles is it down two cups?? Do you check the coolant level when the engine is warm or cold? Check your overflow, its probably in there.
more than likely intake gasket, if your running an edelbrocke intake, or other alum intake use there gasket, its thicker ,seals better, common problem on s.b.c.
It's been pressure checked hot and cold,no leaks to be found.The car does have AC,so it's a possibility the heater core may have a pinhole leak and drain out. The heater core is brand new,but ya never know. Since there's no coolant in the oil and the leak is very small there's no chance of ruining the engine I suppose. Yes,the engine has an new aluminum Weiand intake.Since the block was decked .040 for compression,I checked the intake fit carefully during a mock up before final assembly on the heads.I was satisfied the fit was good,used Felpro blue intake gaskets with a slight bead of sealer around the water ports.When I pulled the heads the intake gaskets showed an even crush pattern all the way around. What is interesting,the car came with a worn 1981 305 that used a small amount of coolant.The only parts from the old engine used on the new one is the heads and water pump.Like I mentioned,the heads were Magnafluxed. Then when I pulled the heads looking for the leak,the machine shop pressure cheked them.A thick plate was bolted to the heads,torqued down,then 100 psi of air pressure and submerged in liquid to look for bubbles. I guess at this point the water pump and heater core might be the usual suspects. Thanks
Edelbrock used to tell you in there instruction not to use the blue gasket with there intake,the intakes I have pulled with blus gasket always showed signs of coolant leakage even with rtv.
The shop that did the machine work does a lot of SBC engines.They told me to use the Felpro blue gaskets and nothing else,especially with iron heads and aluminum intake.Oh well
If it has been pressure checked hot and cold and no leaks show up it may be due to evaporation out of the recovery tank. I'd say just put the cup of coolant in the thing every thousand miles and go look for some real problem to deal with. I do have one question though, How long does it take to get that thousand miles on the truck? That may have a bearing on why the coolant is going down. <input id="gwProxy" type="hidden"><!--Session data--><input onclick="jsCall();" id="jsProxy" type="hidden">
How long to drive a thousand miles? I recently took a road trip of around 800 miles.The coolant didn't seem to go away at all. But driving around town,maybe 200 miles a week,the coolant disappears slightly faster.Maybe shorter trips,heating and cooling the engine,makes it leak more.The coolant recovery tank is stock stuff off an 80's G body Chevy. Other problems to look for?The tranny sounds like shit but that easy to trouble shoot,it's all fucked up inside that iron case Saginaw.
My money's on the heater core or radiator. Especially the radiator, because if you lost a cup a thousand inside the car, you'd have faint antifreeze fog inside all the windows by now or a noticable wet spot in the carpet. If they weep near the radiator tanks, down low, on the front or bottom...it's virtually invisible installed. And if the radiator support has a hole near there, it'll hit the road without leaving a mess on the car. By the time you slop a little coolant out of the lower hose taking the radiator out, you'd never notice the tiny amount of wetness that was already there. And make sure your water pump weep hole is dry. All else fails throw a sealer pellet in like the dealer would've if they installed the engine. But a cup a thousand is a lot of loss for sealer. You're talking a gallon of coolant every oil change. Good luck
I had a 98 lumina that did the same thing and it was an intake gasket, and the hole was small enough for the coolant to atomize out and evaporate before pooling...
Damn, Shifty that is assuming that he changes the oil at the reccomended 16K miles. If my weights and measures math is correct. two cups in a pint, two pints in a quart 4 quarts in a gallon. <input id="gwProxy" type="hidden"><!--Session data--><input onclick="jsCall();" id="jsProxy" type="hidden">
Any bubbles in the radiator with it running? I can tell you from experience that I had a 427 that had been decked, coolant kept leaking out the rear near the distributor, I took the 2 end intake gaskets out and used good quality sealer,(I used the sealant we use for VW oil pans) the problem went away,after that,it was on a drag car .
No bubbles in the radiator. The block end rails were milled so when the block was decked the intake doesn't bottom out.No end rail gaskets used,just RTV sealer.
We had an 89 GMC van with a 305. At about 30,000 miles it began to leak coolant in much the same fashion. It wound up being a crack block in the lifter galley area. According to the GM Zone Manager, GM lightened the weight of the 305 blocks by about 25 lbs in an effort to improve vehicle mileage. This lightening of the blocks lead to thin wall casting conditions that after 20 to 30K miles when a block would 'season' a core shift in the casting of the block occured and sometimes the block would crack. The Manager told me that 95% of the time the core shift-crack would be in the lifter valley. This is one reason why racers like to use seasoned blocks when building high performance engines. Any core shift has already occured in a seasoned block.
i agree with the above. i did a ton of those short blocks back in the day at work. crack in the lifter valley is my vote.
I had the same problem with a 305. Crack in the lifter valley. Block was magna fluxed before build. Crack showed after few months. Anti freeze in oil. Seemed to leak after warmed up. Local OReillys has pressure tester for rent ( money refunded upon return). Crack was on passenger side rear of lifter valley. Second core was cracked too in same place. It took 3 to get a good one. Next time I will go with a 350ci.
I had a similar situation over time it got worse. Filnally pulled heads and had them pressure checked. Sure enugh one head had a small crack in valve area. 350 chevy. Gary
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