it finally happened BHG

[Mk3Les]

Well it finally happened I got the dreaded BHG, well I’m 99.9 percent sure I do anyway. My car isn’t showing the regular symptoms of a BHG, no water in the oil or oil in the radiator, temp is fine no spikes, never over heated. But if I undo the radiator cap while the motor is running I get coolant flowing out and if I rev the motor coolant shoots up about 6 inches . I haven’t done compression or leak down test yet as I don’t think they are going to tell me anything I don’t know already.
The only thing that pisses me off about it is that I have a half built motor with all the good bits nearly ready to go that I had planed having ready for early next year. Now I have to decide if I want to hurry the build along and not put some of the parts in that I wanted too or just slap another head gasket on my current motor. I’m leaning towards doing a BHG repair for now and sticking to my original plan. I guess I should think of it as a right of passage for a 7m owner

 

[DonS1mpson]

Get a leak down/compression test done. If you're not showing any major symptoms there is no use speculating.

Although if there are no major symptoms and you're planning on replacing the engine soon, I have to ask why bother do the HG job? Surely it will last until the beginning of next year if you babied it a bit?

 

[Suprapowaz!(2)]

But if I undo the radiator cap while the motor is running I get coolant flowing out and if I rev the motor coolant shoots up about 6 inches .

Someone correct me if I'm wrong, but I thought that was normal on every car. When you rev it I would think that's your waterpump pushing all that coolant out faster causing that geyser. That coolant is under heat and pressure when the car warms up. That's why you have an radiator cap & overflow container. Back in the early days when you didn't have an overflow container you would only fill the massive radiator only 70-80% full. If you were to fill it up to the top it would overflow out that side tube.

 

[Mk3Les]

Get a leak down/compression test done. If you're not showing any major symptoms there is no use speculating.

Although if there are no major symptoms and you're planning on replacing the engine soon, I have to ask why bother do the HG job? Surely it will last until the beginning of next year if you babied it a bit?

I figure if its pushing coolant out of the top of the radiator than there is a good chance pressure is coming from the cylinders, I could be wrong but I dont think I am. In any case I've had a really good run with this motor Ive been running it hard on 14psi for a while now with a stock head gasket, honestly I thought I would have blown well before now.
As for why do a HG job now? because I cant baby it :naughty: also I've never done one and as crazy as it may sound I think I could learn a bit doing it.

 

[Mk3Les]

Someone correct me if I'm wrong, but I thought that was normal on every car. When you rev it I would think that's your waterpump pushing all that coolant out faster causing that geyser. That coolant is under heat and pressure when the car warms up. That's why you have an radiator cap & overflow container. Back in the early days when you didn't have an overflow container you would only fill the massive radiator only 70-80% full. If you were to fill it up to the top it would overflow out that side tube.

It will do it at idle as well, it's just shoots higher when I rev it.

 

[Suprapowaz!(2)]

It will do it at idle as well, it's just shoots higher when I rev it.

I know, and all cars I've ever owned that that too. When I would change out my thermostat I'd run the car uncapped to try to get all of the air out of the system. When the car started warming up coolant would rise and begin to overflow. When you rev it it would shoot up. The faster you rev it the higher it would go. That doesn't mean you have a BHG.

 

[Mk3Les]

I know, and all cars I've ever owned that that too. When I would change out my thermostat I'd run the car uncapped to try to get all of the air out of the system. When the car started warming up coolant would rise and begin to overflow. When you rev it it would shoot up. The faster you rev it the higher it would go. That doesn't mean you have a BHG.

Hey I could be wrong, it wouldnt be the first time. Maybe I have been a bit too quick to call BHG. Lucky it's not my daily driver so I can take my time and check it out a bit more and I think I will do a leak down test just to put my mind at rest. Thanks for the help

 

[TomFraser]

after running the car really hard, take the radiator cap off if you wanna see a geyser!

that's not a symptom of BHG, and the radiator cap should not be removed unless the car is cool

 

[black89t]

well, i would wait for more symptoms.

what is a dead give away for a bhg between the waterjacket and cylinder is when coolent constantly flows out the overflow, but doesn't get drawn back in to the point that it overflows the overflow. lol. that is if you have a good radiator cap yet it still does it. the reason is the exaust gases are constantly adding more pressure to the system to the point that the radiator cap can't hold. that was the sure sign of my bhg. plus reading the exhaust gas out of my radiator with a ega. :naughty:

 

[Figit090]

yeah that water is going to find the easiest way to flow when the pump adds pressure, if there's a hole in the system...that's the easiest way to flow.

Cap it, and once the air bubbles are properly purged, monitor your overflow bottle...that's my tip. monitor your oil as well.

 

[EOS]

I can't believe no one's mentioned the fluid test kit for this yet. Go out and get the fluid test kit, set it up, and see if the blue fluid in the test cylinder turns yellow. If the blue fluid turns yellow, combustion gas is escaping into your cooling system, indicating you definitely have a BHG. While I'm a big believer in compression and leakdown tests, the fluid test will give you a definite answer in a big hurry...

 

[Mk3Les]

I can't believe no one's mentioned the fluid test kit for this yet. Go out and get the fluid test kit, set it up, and see if the blue fluid in the test cylinder turns yellow. If the blue fluid turns yellow, combustion gas is escaping into your cooling system, indicating you definitely have a BHG. While I'm a big believer in compression and leakdown tests, the fluid test will give you a definite answer in a big hurry...

Cheers for that I'll be doing it over the next couple of days,

 

[hvyman]

im 99% sure your car is fine. symtoms would be overheating, spewing out of over flow, lose of power, mixture, or hearing a waterfall noise out of nowhere when u start it up cold because of mixture and lose of coolent.

when u pull the cap it is just the water pump pushing coolent out of the hole, cause its supposed to be sealed so that doesnt happen,

 

[NgoFcukinWay]

My 1J did that. Geyser water show from the radiator, overheating from the engine, and the overflow tank was boiling. Checked the dipstick and we can see where water and the oil separate. It sucked, but we're pretty sure it's a BHG. Haven't gotten around to taking the head off though. :-\

 

[Dr Chill]

I thought I had a bhg at 1 point , I did a presure test & turns out I had a tiny pin sized hole near the cap on the radiator
Bought a new radiator ,& never had an issue since

 

[Figit090]

I can't believe no one's mentioned the fluid test kit for this yet. Go out and get the fluid test kit, set it up, and see if the blue fluid in the test cylinder turns yellow. If the blue fluid turns yellow, combustion gas is escaping into your cooling system, indicating you definitely have a BHG. While I'm a big believer in compression and leakdown tests, the fluid test will give you a definite answer in a big hurry...

He said it himself;

My car isn’t showing the regular symptoms of a BHG, no water in the oil or oil in the radiator, temp is fine no spikes, never over heated.

From what he describes, doesn't sound like a BHG. Granted, a 30 dollar test kit might be a small price to pay to save you the trouble and pain of overheating or contaminating you oil... but mentioning that right off the bat could possibly be blowing something simple way out of proportion.

I say cap it, keep an eye on fluid levels and the oil clarity, and if there are any hints of actual BHG symptoms, shut it down, and do the test. If the price is cheap enough go ahead and test it now..

Just as long as people reading this down the line don't automatically think that coolant spewing out of their uncapped radiator when you rev your engine means BHG....:nono:

Radiator caps are rated at 13-15psi.... in other words - they're made to hold back a small fountain.

 

[Figit090]

[hijack]

My 1J did that. Geyser water show from the radiator, overheating from the engine, and the overflow tank was boiling. Checked the dipstick and we can see where water and the oil separate. It sucked, but we're pretty sure it's a BHG. Haven't gotten around to taking the head off though. :-\

That sounds, much, much worse. You could see the water on the dipstick? You did drain your oil (and coolant, lol) after that and refrain from ever starting it again, right???

[/hijack]

 

[gtsfirefighter]

Someone correct me if I'm wrong, but I thought that was normal on every car. When you rev it I would think that's your waterpump pushing all that coolant out faster causing that geyser. That coolant is under heat and pressure when the car warms up. That's why you have an radiator cap & overflow container. Back in the early days when you didn't have an overflow container you would only fill the massive radiator only 70-80% full. If you were to fill it up to the top it would overflow out that side tube.

This...

I know, and all cars I've ever owned that that too. When I would change out my thermostat I'd run the car uncapped to try to get all of the air out of the system. When the car started warming up coolant would rise and begin to overflow. When you rev it it would shoot up. The faster you rev it the higher it would go. That doesn't mean you have a BHG.

This...

that's not a symptom of BHG, and the radiator cap should not be removed unless the car is cool

and definetly this...

 

[EOS]

Figit, I'm not saying that he has a BHG, nor am I trying to blow anything out of proportion. All I was saying is that if he's really that worried about it, the fluid test would tell him for sure. I agree that, from what he's describing, it doesn't really sound like a BHG. His car doesn't have any of the usual symptoms--no milkshake oil, no overheating, and no mention of any coolant loss. If he had any of these symptoms, then I'd worry. And yes, any running engine is going to leak coolant out of an uncapped radiator due to the pressure generated by the water pump, and the harder you rev it, the more coolant is going to shoot out. This is normal. As you and others have said, automotive cooling systems are designed to operate with a certain amount of pressure--hence the pressure rating on the radiator cap which you also mentioned. Believe me, the last things I want to do is panic anyone or give anyone incorrect information. I don't want Les or anyone else who'd read this to jump to any conclusions. I was just pointing this out as a fairly cheap option that would tell him for sure before he starts pulling the head on an engine that's potentionally fine. I was really just trying to offer a helpful suggestion that could save him a lot of work...

 

[SupraMario]

car is cool, T stat = closed.
car is warm, T stat is open...
Dunno why you think this is BHG...