Help! During radiator filling the level won't decrease

[speedbird1229]

Coolant having problems leaving to the reservoir / cooling pressure

Hi,

I've been troubleshooting my cooling system problems which mainly show up by relatively high pressure in the system all the time. The upper rad hose is constantly quite hard (not possible to compress very much by hand).

I've done several tests, also tried to figure out if head gasket or cylinder head leak might exist. Tests done so far:

• Running without radiator cap - no air bubbles in the coolant
• No signs of oil in coolant, coolant in oil or white smoke from the exhaust
• Radiator pressure tester - showed constant pressure and the gauge was stable, no jumping around even when adding throttle
• Combustion gas tester - ran the test through the radiator which used a coloured liquid and in case of positive result, I should have seen the blue liquid turn into yellow. Result: no change in color

Today I ran without the radiator cap and tried to check the coolant level properly (fill it up more in case the level drops) while also burbing out possible air pockets from the system. Even when the thermostat hadn't opened yet, the coolant kept slowly dripping out from the radiator so that I had to keep a towel underneath not to make a mess on the garage floor. It began dripping right after start-up and kept going even when the engine was totally warm.

I also can't understand why my reservoir really doesn't want to fill up at all, it does increase in level by about 1/4 of an inch or up to 1/2 inches. But shouldn't it be more? I've checked the reservoir hose and the whole reservoir piping for any blockage and I've replaced the radiator cap.

Would you still bet on a head gasket problem although there are no usual signs of it? I'm planning to have the gaskets and some other components replaced before Summer but I'm simply trying to do some troubleshooting before.

Thanks for any advice!

P.S.

I changed the title but it won't change in the thread listing. I believe the coolant level shouldn't decrease in the radiator if the system is completely filled up.

 

[76okievette]

Are you sure the water pump is circulating the water correctly, I take the car does not run hot but it seems like a cirulation issue to me.

 

[speedbird1229]

Are you sure the water pump is circulating the water correctly, I take the car does not run hot but it seems like a cirulation issue to me.

Not completely sure... Any way to test it?

The car doesn't run hot at all, I've never seen it go past 200-210. Usually stays perhaps at 180 or so.

 

[Jack]

First, suggest you verify temps with a separate, known t'meter ... so you KNOW what temps are ... dash gages not always reliable.

I'm usually pretty good on this stuff ... but I had one recently yank my chain ... over & over & over.

Our own car ... Lincoln Town car we've had nearly 7 years ... great cars, we have 2. I maintain & keep our cooling systems very clean.

Over a year ago, I changed out defective OE plastic intake manifold & installed new MotoRad t'stat ... purged air w/fresh coolant ... everything AOK for about a year when ...

1 year old "MotoRad fail-safe" t'stat stuck closed in it & it overheated ... did not seem real bad but ya never know.

I changed out t'stat to standard Stant ... all fresh Dh2o & AF ... I was "sure" I had purged all air out of system ... then I experienced all the same probs you describe above. First, I changed out the rad cap ... but No fix ... then I was seriously thinking a bad head/gasket ... even though tests denied that. This crap went on for about a month. But of course, I was "sure" I had all air out of system. Well, turns out I was surely wrong & it was air ... once I worked at that with renewed vigor, I got more air out & more AF in. Everything's been AOK for a couple months.

Air will compress & decompress ... but coolant does not.
Suggest you accept you may Not have gotten all the air purged out ... and give it another good hard try or 2.

And those hi-tech MotoRad never-fail fail-safe t'stat's????? IMHO BS JUNK! As for my initial air purging score ... also BS Junk!

Verify temps ... change out rad cap.... Get the nose of that vette up & tail down ... get it hot ... work at it ... & watch it like a hawk.

 

[speedbird1229]

First, suggest you verify temps with a separate, known t'meter ... so you KNOW what temps are ... dash gages not always reliable.

I'm usually pretty good on this stuff ... but I had one recently yank my chain ... over & over & over.

Our own car ... Lincoln Town car we've had nearly 7 years ... great cars, we have 2. I maintain & keep our cooling systems very clean.

Over a year ago, I changed out defective OE plastic intake manifold & installed new MotoRad t'stat ... purged air w/fresh coolant ... everything AOK for about a year when ...

1 year old "MotoRad fail-safe" t'stat stuck closed in it & it overheated ... did not seem real bad but ya never know.

I changed out t'stat to standard Stant ... all fresh Dh2o & AF ... I was "sure" I had purged all air out of system ... then I experienced all the same probs you describe above. First, I changed out the rad cap ... but No fix ... then I was seriously thinking a bad head/gasket ... even though tests denied that. This crap went on for about a month. But of course, I was "sure" I had all air out of system. Well, turns out I was surely wrong & it was air ... once I worked at that with renewed vigor, I got more air out & more AF in. Everything's been AOK for a couple months.

Air will compress & decompress ... but coolant does not.
Suggest you accept you may Not have gotten all the air purged out ... and give it another good hard try or 2.

And those hi-tech MotoRad never-fail fail-safe t'stat's????? IMHO BS JUNK! As for my initial air purging score ... also BS Junk!

Verify temps ... change out rad cap.... Get the nose of that vette up & tail down ... get it hot ... work at it ... & watch it like a hawk.

Thanks for the tips, Jack! You've got some good points there, I especially like the statement that you had similar symptoms on the Town Car. Been looking for someone quite long time who has had any similar symptoms, haven't had any luck until now. I will try getting more of that air out. Is it the standard procedure - warm up the engine until T-stat opens, rad cap off all the time, and once engine is warm start squeezing the top rad hose?

And when you say air is compressible, do you suggest that if there is too much air in the system, the air is compressed and kept inside the system, while the coolant without air would not compress and shoot into the reservoir instead?

I'm also wondering if the coolant is supposed to drip out from the radiator while the engine is running.

 

[Vettehead Mikey]

Hi,

I've been troubleshooting my cooling system problems which mainly show up by relatively high pressure in the system all the time. The upper rad hose is constantly quite hard (not possible to compress very much by hand).

Still trying to fix things that are not broken I see.................:eyerole Third strike you're out! Good Luck

 

[speedbird1229]

You're right, Mikey. It's just that nobody has really told me that the symptoms I'm experiencing are normal for this engine operation. I think Mike Ward in Corvette Forums once told that the hose should be hard and I don't even care about the hose that much but simply that the reservoir won't fill up again when warming up the engine in same conditions. If somebody here could just describe a bit how his L-48 operates when it warms up from cool, I would be really glad. Since I've ran all kinds of tests and haven't gotten any results, if these symptoms are not completely normal it seems like my only way out is taking the engine apart. I want to get it perfect or running as it's meant to be. In case it's really meant to be pressurizing the cooling system to rather high level already when cold, then I will be satisfied. However, nobody has so far confirmed it.

If somebody thinks I started this topic here simply because in Corvette Forums I didn't get much attention anymore with this matter, this is not true I just believe that here are some different people around and I want to see if they know something new.

 

[Vettehead Mikey]

As determined in your posts on that other forum, your car is now operating as per factory design.

You've eliminated the faulty radiator cap, learned how to attach the radiator hose correctly and have driven the car successfully on numerous occasions with no symptoms of any new problems.

Please ignore the bad information that your local mechanic gave you and you'll be able to relax and enjoy the car.

 

[Wayne robson]

may also help

Hi all, its been a while, but had to mention this,one of isues that arise when filling the radiator,is removing air,and the bigest mistake made is in the heater system, as it is heating up, you have to turn your heater to the on position, this then allows the freon to travel through the system and also removes any air inside , but what can also happen if the heater valve is rusted and not operating correctly the freon will not pass through and just sits in the hoses, with air.While doing all this radiator cap should be on, and after its reached operating temp, stop for approx 10 minutes check and add freon to the top,of radiator and approx quarter overflow bottle.some times have to do this a couple of times.

 

[Bob Chadwick]

I'm with Mikey. What exactly is the problem? The car runs at normal temperatures with the cooling system operating properly. The only issue I see is the dripping coolant and I'm not sure what you are referring to.

If it were my car, I would fill the radiator and the overflow tank to within the normal range and drive it. Monitor the overflow tank and make sure that the coolant stays within the proper range.

 

[entropy454]

Hi all, its been a while, but had to mention this,one of isues that arise when filling the radiator,is removing air,and the bigest mistake made is in the heater system, as it is heating up, you have to turn your heater to the on position, this then allows the freon to travel through the system and also removes any air inside , but what can also happen if the heater valve is rusted and not operating correctly the freon will not pass through and just sits in the hoses, with air.While doing all this radiator cap should be on, and after its reached operating temp, stop for approx 10 minutes check and add freon to the top,of radiator and approx quarter overflow bottle.some times have to do this a couple of times.

I assume you mean coolant and not freon? :confused

 

[speedbird1229]

Thank you guys. The basic problem was that I've had the top radiator hose shoot off the radiator after an hour driving or so, and the previous owner also told that he had it happen a few times and couldn't solve the problem. We took the car to a couple of local mechanics who have been doing US cars for a long time (not many Corvettes specifically, but I guess they assume the engines are similar). What they did was that they squeezed the top radiator hose by hand and told me that the hose seems to be too hard for normal operation. I was already told in Corvette Forum to stop squeezing the darn hose, but it does roughly indicate the pressure currently in the system, I believe. Recently I found out that the radiator hose might have not been secured properly with the clamp and I re-tightened it to the location where it sits in the lowest spot of the radiator pipe, between the higher levels of the pipe. I can't show the photo right now, but I will do it later.

I couldn't drive the car after this very much, so it's hard to give any real results. I assume the upper hose is now pretty tight but I hope it won't break from somewhere else.

Long story short, I know that most of you guys here and in the other forum are smarter than an average mechanic, but I thought they should at least know about such simple things and if they say it's not normal, I hence began investigating.

 

[Wayne robson]

sorry yes coolant.

 

[Bob Chadwick]

Thank you guys. The basic problem was that I've had the top radiator hose shoot off the radiator after an hour driving or so, and the previous owner also told that he had it happen a few times and couldn't solve the problem.

I read your first post to indicate that radiator pressure was tested and found to be normal. If you had too much pressure in the system the radiator cap, which is indicated to be in good working order, would blow and allow coolant to be released.

 

[speedbird1229]

This seems logical, doesn't it. I have the same opinion and it's just that the mechanics told me the 15 psi pressure which the radiator cap has, is not a mandatory pressure in the system but it's simply the limit when the coolant is released. They told me that the hose generally needs to be rather soft because the system doesn't need to run at so high pressure when the engine is warmed up. I really want to test again with the pressure tester and see what kind of pressure 15 psi is to the hose hardness and such.

Does the mechanics story sound bulls***?

Is there any chance somebody could capture a video for me - showing coolant level in reservoir before start, starting up the engine from cold with open hood, then after a few minutes squeeze the top hose to indicate how hard it is and the coolant level in reservoir when the thermostat has opened and engine is warm.

 

[Vette79]

What has been done so far to resolve this issue? You did replace the radiator cap right? Why? You have tightened all of the clamps on all of the hoses? The coolant level in the radiator is what? Are you losing coolant?

 

[speedbird1229]

What has been done so far to resolve this issue? You did replace the radiator cap right? Why? You have tightened all of the clamps on all of the hoses? The coolant level in the radiator is what? Are you losing coolant?

I have thrown all kinds of tests at her as I also mentioned in the first post. The radiator cap was replaced and I've tested about 3 different caps on it. One was an old used cap that I just tested but the other two were quite new and then brand new (that I now use on the Vette). The cap certainly works backwards because I've seen the coolant level decrease from the reservoir after the engine has cooled down from warm.

All clamps are tightened, there is a new radiator on the car (installed last summer) and I believe all the hoses are replaced.

Coolant level in radiator has always been to the neck. I've also done the re-filling procedure to run it without the cap and then re-fill once the engine draws it from the radiator.

I'm not loosing coolant in general, there are no leaks when the car has parked in the garage.

 

[Vettehead Mikey]

This seems logical, doesn't it. I have the same opinion and it's just that the mechanics told me the 15 psi pressure which the radiator cap has, is not a mandatory pressure in the system but it's simply the limit when the coolant is released. They told me that the hose generally needs to be rather soft because the system doesn't need to run at so high pressure when the engine is warmed up. I really want to test again with the pressure tester and see what kind of pressure 15 psi is to the hose hardness and such.

Does the mechanics story sound bulls***?

For the umpteenth time yes. I wouldn't let this guy work on any vehicle of mine. Corvettes are not unique in the function of their cooling system, virtually any car or truck built from the 70s onwards has the same basic set up.

Stop chasing ghosts.

 

[Evolution1980]

I'm kinda with the rest of the group on this one. If you've secured the hose so that it doesn't blow off now, then it doesn't really sound like much of a problem.
You sound like you've double-checked everything and replaced most of the usual stuff and then some.
Checking for line pressure by squeezing the radiator hose when hot isn't exactly a great measurement tool. I know on my car that the radiator hose is naturally quite a bit sturdier than the radiator hose use on a 4-banger daily driver. Even when hot, my radiator hose doesn't have much give.

If the car ain't overheating and you aren't losing any more coolant, then be satisfied that you have a properly working vehicle.

As for the reservoir not having much coolant in it when the car is up to temps, same here. Mine almost never has coolant in it, even on the hottest days of 100°+ outside temps. But I know my system is 100% good.
If you are concerned about adding coolant to the system without popping the radiator cap, just put coolant in the overflow tank and let the system suck up the extra juice on it's own. Whatever it doesn't need will remain in the overflow.

Sounds like you're good to go, guy!

 

[Jack]

I'm also wondering if the coolant is supposed to drip out from the radiator while the engine is running. If it has a reservoir, NO, simply NO.

BUT FIRST find & close all leaks.
Then, again, verify temps w/ a known separate t'meter.

Is it the standard procedure - warm up the engine until T-stat opens, rad cap off all the time, and once engine is warm start squeezing the top rad hose? Yes ... BUT elevate the nose of car ... air will TRY to rise to top ... & as another said ... if the car has a heater/coolant VALVE ... ensure coolant is coursing THRU heater. It's easier to get air out of typical vette when its nose is up ... important. When you think you're done ... LEAVE nose up ... come back when it's fully-cooled & check it again w/ nose up.

And when you say air is compressible, do you suggest that if there is too much air in the system, the air is compressed and kept inside the system, while the coolant without air would not compress and shoot into the reservoir instead? I'm saying just what I said ... and that an air "pocket" trapped deep in motor will expand when heated... causing hose to be TOO hard ... (may/may not blow hose off/push coolant out). When it cools the air pocket contracts & pressure returns to normal. Coolant does expand&contract but at such a small rate I don't consider it here.

I cannot clarify this further.