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Head Gasket? Thermostat?

2971 Views 19 Replies 13 Participants Last post by  Phireant
I recently bought a '91 Legend with the understanding that it had a blown head gasket. However, when I got it home, there was no sign of this problem - Ran great, no oil in coolant, no coolant in oil, doesn't use coolant, no smoke, compression is good in all cylinders, coolant system is not overpressurized. We've put 2k miles on it with no problems. Nothing until yesterday, when it started acting up on my wife. When I checked out the car last night, it was very low on anti-freeze. I filled it up, and let the car sit and idle. after a while it started to heat up, and I noticed that the lower radiator hose was still cold. Shortly after that, the cooling fans came on, and the air coming off the radiator was cold while the upper hose was very hot. I replaced the thermostat, but when tested, the old thermo seemed to be working. After installing the new thermo, I let the car warm up, and it was behaving the same way as with the other thermo. At that point I was running out of time. I needed a quick temporary fix, so I gutted the old thermo so that it would always be open, and installed it. I drove the car for about an hour and it seemed fine. Drove it to work today and it's still fine. I'm a little confused now. Shouldn't the thermo open before the fans kick on? There's no coolant leak that I can find. Can the head gasket use coolant intermittantly? Can anybody shed some light on this for me? Sorry for the long post, but any ideas?
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I'm curious as to how it came about.... of your understanding that it had blown head gasket in the first place.

A sure fire way to tell if your car does have a blown HG is to have your mechanic test the fumes in the coolant system. They put a cap and hose combo that leads to a bench machine - this machine will test the vapors.

Because you have done a leak down....

It is possible for your seals on your waterpump or the waterpump to have she~ite the bed altogether, thus causing the low fluid. The gasket (if you can call it that) is a long round rubber band (similiar to what holds a screen tight on your screen door).

I don't know though - it does sound like an HG problem that I'm trying to avoid calling (it). Perhaps the previous owners ran some stop leak and that stop leak has finally "ran dry." Try putting some more in the system BEFORE paying out the arse.

McKenzie, care to comment.

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The previous owner said it was using some coolant, and somebody had told him it had a blown head gasket. I've been wrenching on engines for 25 years, and I've never seen a blown head gasket that showed absolutely no symptoms. I haven't had the coolant tested yet, but in the past I've always been able to see oil or carbon in the coolant, and this coolant is perfectly clean.
Up until yesterday, I was of the opinion that even if it has a blow HG, that I wasn't about to do anything about it until it started causing a problem. What confuses me is the sudden loss of massive amounts of coolant without any other sign such as smoke, a leak, or a poorly running engine. Now that I took the thermostat out, it runs fine and appears to not be using coolant anymore. I know some of this makes little if any sense, but it is exactly what I am experiencing. I didn't really follow what you said about the water pump - How can it use coolant without leaking?
My statement was a hypothesis about where your coolant could be going.

Despite your statement...

"What confuses me is the sudden loss of massive amounts of coolant without any other sign such as smoke, a leak, or a poorly running engine."

obviously the coolant is going somewhere, so (How can it use coolant without leaking?) doesn't make sense?

You have me scratching my head.

Actually, my comment "how can it be using coolant without leaking" was in reference to the water pump. As far as I know, the only way a water pump can use up coolant is for it to leak, and I have no leaks. Am I missing something?
JimV, your problem is really strange. Your using up coolant, however, there are no viseable signs of leaking (or burning). I would highly suggest you have your coolant vapor tested and then I would have your exhaust also tested too.

Could it be leaking from the Heater core inside the car?
KNLNGUS: I guess at this point I would have to agree. Thanks for the information.

KURIZMA: I don't think so. I'm pretty sure I'd either see it or smell it, and there is no sign either way.
I have the same symptoms as you. I have no whit smoke coming from the exhaust and a hydro carbon test showed no signs of fluid contamination.

I lose coolant but what happens when you overheat while you're driving, all the hot coolant is going through your upper rad hose into your rad. Because of too much air in the system, the pump cannot move the cold coolant from the lower rad hose into the engine therefore the hot coolant in the rad is getting so hot and also the air bubbles in the system are expanding exponantially due to the heat that your overflow reservoir gets flooded with coolant to the point that it cannot hold no more and starts squirting coolant under its lid due to the high pressure. All this happens as your needle goes to red while you're driving.

You pull over and can still see bubbling in your overflow reservoir while your upper rad hose is burning and your lower hose is cold.

My mechanic concluded my head gasket was blown by doing a pressure test on each cylendar. What he did was take out the spark plugs and one at a time, he would blow 60psi into a cylandar, but before he did that he would bring the cylender to "top dead centre" position (all the valves are closed) and with the radiator cap off, he'd watch the fluid level in the rad. With my #6 cylnder, the fluid level rised as he put pressure into that cylender.

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I've done a compression test, but won't have time to do the cylinder pressurizing test until Saturday. Did you get your car repaired? If so, how does it run after the repair? My engine generally runs good, but is not as smooth as I would expect (my civic si runs smoother). I'm wondering if the hg repair improved that at all.
Where in NE Ohio are you? Near Akron/Canton? If so, I lived there all my life, I can refer you to a good shop to get your car checked out. email me if you want.

Hey i have a similar problem

The only differnce is I smell burning coolant.

But no leaks, no white smoke, no coolant contamination nothing

What gives ?
my car act kinda the same
i thing is getting overheated but my temp is in normal
half of my radiator is hot and sec. half is cold the top is hot
is that normal ? and my fans are going on after 10 min agresive driving and thay stay on for like 30 min. is that normal ?

If there are no leaks and if the radiator top tank does not have a hairline crack, then the loss of coolant has to be due to a failing headgasket.
When the Head Gasket went in my 91 LS, it was months before someone actually knew what it was. The symptoms were so slight, and so misleading. The exhaust gas test proved negative, still ran good, little loss of antifreeze, etc..

It wasnt until the last month that it got really bad.... boiling over bigtime, loss of rad juice, and a few other odd things.... loss of warm air, temp guage rising and falling rapidly. Finally a rad shop told me that that was the problem (HG).

So I can tell you this...... more than likely, your HG is pooched:( .
It is showing the same symptoms as my car was. aAt first I was going to say a failing watepump, or seal, but your symptoms are very common to the failing HGs on these cars.... almost phantom HG failure.

From what you say, you seem to know a fair bit about automobiles..... so you should know that procrastination will cost you money in these cases. My block had a crack in between the cylinder liners so I put it back together with the problem fixed, and sold it. I think it was in part due to leaving the repair for so long..... so I would get on that while you are at it, and give it the other maintenance items as well such as plugs, H20 pump, T> belt, belts, fluids etc.... then you will seew how nice the car is supoosed to run.... good luck
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not in my acura...but my cherokee I was losing fluid fast with nothing to show on pressure testing. then months later after adding a gallon of fluid every week...i came out and saw fluid under my front. cranked her up and no leaks...could not find it .....
after an hour at the radiator shop it finally got hot enough...come to find out I had a small hairline crack at very top edge of the radiator...and when the fluid gets hot enough to bubble up to the top it would finally leak out...or overflow and come out of my resevoir. My triumph TR6 was notorious for head gaskets but you could always smell the fluid burning on the engine...and started seeing it in oil.
actually i'm losing radiator fluid out of my resivoir tank. ONe time i checked my resivoir tank was almost empty.........i'm not sure if its a headgasket problem or not......i only see white smoke when the weather is wet. I do on the otherhand smell some sweetness when i turn on my heat on. can anyone shed some light? I have never seen the needle move at all to any overheating level. Since I bought the car I put around 800 miles on has 114k
The sweetness you smell is the coolant that is overflowing in your engine compartment.
As for your reservoir overflow, is the coolant boiling out through there or is the coolant disappearing and being sucked back into the radiator?
If the coolant is boiling out of the reservoir, try changing your radiator cap. Could be as simple as that.
If your loosing coolant and have no leaks, then you know what you need to do, pressure test, compression test etc.
oh gosh i hope that i don't have a BHG. Recently i have noticed that air had been getting into my coolant. Because i keep getting "cold heat" about every two weeks after i bleed the coolant. Also my resoivoir is not over flowing, but it seems to be getting fuller everytime i look at it... not too sure about what is going on there. So i thougth maybe it was just the radiator cap, i went to the acura dealer to get a oem radiator cap ($22.47) and put that on and bleed the air out of the coolant. That was about a week or two ago. and not i'm getting the cold heat again. I haven't had time to check my resovior but i'm guessing it's getting fuller once again(slowly but surely) just help with this...
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