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Are cracked cylinder heads repairable?


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You gotta love a flow chart A pressure test may help you to see where the leak is. Water in a cracked head generally makes the oil look milky. I suspect that you suspect a cracked or warped head because the car has over heated at some time. I hope the flowchart helps. Course of action is to determine where the leak then decide the next step. You can try the "mechanic in a can" solution but these can cause more harm than good in the long term.

Posted on Jan 16, 2013


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Posted on Jan 02, 2017

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SOURCE: Can a warped or cracked head cause an external

I think he means that a warped or cracked head can overpressurise the cooling system and blow out the seal (maybe). If the radiator cap is doing it's job, I'd expect to see coolant released there at a lower pressure than the water pump seal. If the radiator is bubbling air, I'd expect a head or head gasket problem as well...hope this helps.

Posted on Sep 13, 2009

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SOURCE: oil in overflow bottle. one guy said head gasket $

Unfortunately, the guy is probably correct. Actually, a head gasket would likely be best case. Depending on where and the severity of the crack(s), oil may only bleed into the coolant system when the engine is hot and the iron / aluminum has expanded. There aren't too many ways for engine oil to find its way into your overflow bottle. The worse news is that your heads and / or block may be cracked between the oil and water passages. This would be MAJOR...

I've heard that Ford is quietly recalling these vans for a different reason. I'd suggest that you check your VIN w/ a local dealer and hope that yours is part of the recall.

Good luck.

Posted on Jan 15, 2011

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SOURCE: 1991 Lincoln Town car overheating

The year of the vehicle, rusty liquid, and overheating, says your radiator could use a replacement. If it was your water pump, you would have liquid coming out of the water pump itself.

Posted on May 31, 2009

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SOURCE: coolant blowing out of radiator into overflow bottle at start up.

Typically would not overheat until enough coolant was lost. Find out if they mag fluxed the heads, or had it done. A lot of shops rebuild without doing this step as it's expensive. If they got a rebuilt head, again they need to know if it was mag-fluxed.
It's harder to mag flux the block while in the vehicle and assembled.

Posted on Dec 12, 2009

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SOURCE: Car overheating, coolant blowing out of overflow

without knowing much about the particulars of the car I am at first inclined to go with what the computer says. HOWEVER I also happen to know if you have a bad or stuck thermostat not letting the coolant flow correctly it too can trick the computer into a head gasket error code. Most times you can get a new thermostat for less than $15.00 and change it yourself. It's usually 2 bolts. If you change it and still get the same result look at it as cheap insurance and then you'll know someone isn't trying to take advantage of you by telling you it's head gasket when it really isn't. Head gasket job's aren't cheap I would want to make sure before I spent that kind of money.

Posted on Jul 11, 2012

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Why is my 2001 toyota sienna overheating?

Have a compression test done on each cylinder. Possibly a blown headgasket or cracked head

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How to stop water from bubbling in the expansion bottle after changing head gasket water pump heat sender unit

why did you need to change the head gasket in the first place ?
There may be a reason the gasket failed like a crack in the head or a warp in the head of the engine.

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The engine overheats and uses up water very quickly

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What is causing overheating?

Check your oil dipstick. If there's a grey/creamy sludge on it that means water is finding its way into the oil system. Your cylinder head gasket/cylinder head is faulty.

Fill your coolant bottle. Leave the top off. Start the engine and watch the coolant level. To begin with, you will see air bubbles escaping. This is normal. If bubbles continually appear or the coolant level 'shakes' violently, this indicates that exhaust gas is finding its way into the cooling system via a cracked cylinder head/faulty head gasket. Also look at the exhaust gas - is it clouds of white? If so - that's steam from water being burnt in the engine - a head problem.

Over heating is a sign of a cracked cylinder head/faulty head gasket.

The other causes of overheating includes a stuck thermostat or a leaking/blocked radiator.

If there's no sign of a coolant leak underneath your vehicle - suspect the cylinder head gasket

Mar 03, 2016 | 2006 Opel Corsa Utility

1 Answer


Doesn't sound like it ran hot enough or long enough to crack or warp the head. If there is a crack, the engine will continue to overheat. If a warped head, car would probably run rough, the affected cylinders would likely have little or no compression, there would be a noticeable miss, and overheating would continue.
Why the low coolant? It's a sealed system, so should never have to add coolant, other than a small loss from evaporation in the overflow tank. Monitor the level closely for the next few days. Note the level in the overflow tank to see if it drops over time. Leaks can be external anywhere in the coolant system-engine, radiator, hoses, heater core- or internal in the engine-head gasket failures can cause coolant in the cylinders (white smoke out the exhaust), or coolant in the oil (oil will have a milky brown look to it), or oil in the coolant (will see traces of oil in the radiator).
A couple of tests may be called for. A pressure test of the coolant system will check if the system holds pressure as it should-about 15 psi. If pressure does not hold, there is a leak somewhere. Water pumps usually leak through the weep hole when they fail. A radiator leak would show up when pressure is applied. If pressure does hold, check if you have a good radiator cap-the cap is what seals the system so pressure will maintain. Coolant under pressure raises it's boiling point by about 10 degrees, so is critical to keep the system under pressure.
If you suspect further problems-losing coolant or continued overheating-then have the chemical test done to check for exhaust gasses in the coolant. Basically a check if the head gasket is good, a simple test done at the radiator cap opening with a special fluid that changes color if hydrocarbons are present in the cooling system.
Or you could have a compression test of the cylinders to check the internal mechanical condition-not only tells you if head gasket is good, also tells you a lot about engine condition-even,. balanced, good compression in all cylinders translates into good power output-rings are good, valves are sealing good, all systems go.
The cooling system: water pump, thermostat, radiator, hoses, heater core and hoses, radiator cap, overflow tank, and the cooling fans and associated wiring. Make sure everything is working right and you'll be good to go.

Sep 17, 2013 | 1994 Toyota Camry

1 Answer

My 98 firebird tail pipe blows white smoke and water out the tail pipe then as i let it sit for 30 minutes the engine gets hotter then gas like smile and heavier smoke come out the tail pipe it also s

One of the main causes of white exhaust smoke and coolant loss is a cracked or warped cylinder head, a cracked engine block, or head gasket failure caused by overheating. A cracked head may allow coolant to leak into one or more cylinders or into the combustion chamber of the engine. Dirty coolant, a poorly maintained cooling system, a low coolant level, or a non-functioning cooling fan can cause engine overheating. In addition, engine wear can eventually cause the gaskets to lose their capacity to seal properly allowing internal coolant loss. Intake manifold gasket and head gasket failures are two of the most common sources of internal coolant loss caused by engine wear.

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Aug 21, 2012 | Pontiac Firebird Cars & Trucks

2 Answers

Unexplained coolant loss. Cyl. pressures good don't thing it is head gasket. No visible leaks. Goes thru resovoir daily.

If there isn't a puddle of coolant forming on the driveway after the car sits for awhile and there isn't a puddle inside the passenger compartment, then the problem must lie in the cylinder head or engine block.

Jan 02, 2011 | Daewoo Nubira Cars & Trucks

4 Answers

Over heat

If the head gasket goes water is allowed to seep into the cylinders and then out of the exhaust.

Once the level has dropped enough the car overheats

Or the water is pressurised in the radiator from the compression of the engine and it is forced out of the overflow leading to coolant loss and overheating

Sep 16, 2009 | 1996 Ford Contour

2 Answers


If the temperature gauge isn't moving you are either completely out of coolant or your coolant isn't circulating.

It would be worth your time to check your coolant level, then look for leaks. If you are also noticing that your heater doesn't work it would help to confirm this diagnosis.

Could be several things causing a lack of circulation: a blockage in your coolant lines somewhere, your water pump is not functioning, or you have a blown head gasket or warped cylinder head. An engine overheat can also cause the blown head gasket and/or warped cylinder head as well, so you would be best served by driving your car as little as possible until you've diagnosed the problem.

If you are out of coolant, you should check a few places for leaks. Obviously at your main coolant lines, but also along the heater core is a good place to check. If you can't find any obvious leaks, you may want to try flushing your radiator, since it's relatively simple to do and certainly can't hurt. Also change your oil: if it comes out looking opaque and like a milkshake, you're getting coolant into your cylinders, which means you've blown the head gasket or warped the cylinder head.


Aug 13, 2008 | 1993 Volvo 960

1 Answer


There's many causes of overheating (on all cars..).
The first and most obvious thing I would do after checking the coolant level in the radiator expansion tank was at the maximum level, would be to check for coolant leaks while the engine is running with a 'few revs' on a warm engine.

Hoses can split internally and also become soft and collapse internally through age. When this happens the hose becomes blocked and prevents the coolant from passing through easily. If a hose feels 'soggy'/soft and is easily squeezed flat by hand, it's suspect.

Coolant can also leak from the heater hoses, the heater unit, the bearings/seal on the water pump and of course the radiator. Nor is it always easy to see a leak let alone find it. If the in-car heater unit is leaking the carpets may be wet at times and sometimes, the windows may mist up when the car is standing - this is the coolant condensing on the interior of the glass.

Ok... you can't see any leaks while the engine is running. Is the car losing coolant when it stands? Or is it losing coolant when the engine is running? ( a split hose may only leak when it is pressurised with warm coolant) Or is it just losing coolant when it overheats?

Remove the cap from the radiator expansion tank when the engine is cold. Make sure that the water level is at maximum. Leave the expansion tank cap off. Leave the car standing overnight and next morning look at the coolant level. If it has dropped there's probably an unidentified leak somewhere. If the coolant level hasn't dropped, it points towards a problem that is caused when the engine runs.

With the expansion tank cap still off (get a flashlight to help you) start the engine and peek into the expansion tank. Watch what happens to the coolant (though do keep your face out of harm's way). As the coolant begins to circulate air bubbles will probably appear within the coolant. This is quite normal - air is 'bleeding out' of the coolant as it circulates. The air bubbles should stop after a couple of minutes.

As the coolant warms it will rise up in the expansion tank (keep your face out of the way ..). If the air bubbles continually appear or, there's a constant and continual stream of bubbles or a 'violent bubbling' then this may point to problems with a warped/cracked cylinder head or leaking head gasket (or both).

A defective cylinder head/gasket can allow exhaust gasses to be pumped into the water jacket (the coolant system) simply by the compression action of the pistons. Just like a hypodermic needle can inject air into your bloodstream. When this happens - pressurised exhaust gasses being forced into the cooling system - the cooling system itself becomes pressurised.

The coolant itself can find its way into the cylinders where it is vapourized and pumped out of the exhaust along with the exhaust gases. If you can't find any leaks - the missing coolant may be going out of the exhaust as steam (though you may not see any steam as such). A classic sign of cylinder head/gasket problems is overheating. Check your oil - if there's a yellowish/creamy mayonnaise/sludge that's another sign of head problems. The sludge is caused by coolant finding its way into the oil.

No leaks, no bubbling expansion tank - and if you're happy that there isn't a head/gasket problem, turn your attention to the radiator, thermostat and water pump.

With age, cooling fins on the radiator can corrode and crumble away, reducing its cooling ability. Whilst coolant still passes through the radiator it isn't being cooled sufficiently. Check the condition of your radiator. Radiators can also suffer from an internal blockage. With a warm engine that is switched OFF, feel the top radiator hose - it will be hot. Then feel the bottom radiator hose. If the bottom hose is cold it indicates that coolant is not finding its way down/being circulated maybe due to a radiator blockage or failed thermostat. Flushing may cure blockages.

A thermostat can fail in the 'closed' position. When this happens coolant is prevented from getting into the radiator via the top hose. The coolant in the block then overheats causing the temperature gauge to hit red. The thermostat is located (usually - it depends on make/model variations) on the cylinder head where the top radiator hose joins. They're very easy and cheap to replace.

The water pump can leak water when the bearings/seal fail. Coolant that slowly drips onto a warm engine soon evaporates making detection difficult. Way back, some water pumps had plastic impellers (perhaps they still do). The plastic vanes on the impellers used to wear away with age and use, leaving a spindle spinning uselessly in the coolant - not pumping it. Think of an airplane with a propeller. If the propeller blades wore away the 'nose cone' would just spin uselessly and no air would get moved ..

Before jumping to any conclusions and replacing parts unnecessarily, get a workshop to look at the car. A workshop will be able to test the coolant for exhaust contaminants within minutes (or pressure test the coolant system. If there's contaminants present - there's a head problem. No contaminants present - the fault lies elsewhere.

Back to the cylinder head:
It's a 2-3 day job to do the work yourself. A cylinder head must be skimmed prior to refitting. Refitting an unskimmed cylinder head back onto an engine cures nothing.

Years ago, here in the UK, there was a liquid additive called 'head weld' (and one for the radiator called 'radweld') which provided a TEMPORARY get-you-home fix. Head-weld was a liquid added to the coolant system. It contained fine particles in suspension ... these particles were carried to the crack/leak in the cylinder head and formed a 'dam' that was held in place by the water pressure until they (the particles) hardened.

Recently I noticed an advert for a product called 'steelseal' - here in the UK. The advertising blurb claims that it uses new technology without particles to form a permanent fix for cylinder heads/gaskets. It's a clear liquid that you just pour into the cooling system and then run the engine until its fixed. I've never tried it. At around 45 dollars a bottle it isn't cheap, though if it does what is claimed then it's a hell of a lot cheaper than having a cylinder head/gasket fixed. No doubt there are similar products on the shelves of car accessory and parts shops near you.

Aug 12, 2008 | 1992 Volvo 960

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