A car's engine functions as its heart, and the cylinder head is one of the most crucial parts of that heart. Sadly, this part is prone to cracking, especially if the engine has been used for many years. So, what can you do about it? Can it be repaired, or do you need an outright replacement?
A cracked cylinder head can be repaired using one of two methods: pinning or welding. Pinning is simple and affordable and prevents the crack from growing larger. Welding eliminates the crack by filling it but is more expensive.
Choosing between repairing or replacing will depend on the cost difference, as some engine cylinder heads are cheaper than others.
In this guide, we’ll look more closely at cylinder cracks, how they’re fixed, and whether you should get a replacement instead.
What Causes a Cylinder Head to Crack?
Before going for the repair or replacement of a cylinder head, do you know what caused those cracks in the first place? As you’ll see below, there are direct and indirect causes behind cylinder cracks. This means that a problem elsewhere can also lead to cracks in the cylinder head.
Direct Causes of Cylinder Head Crack: Overheating
The most common and direct cause of a cracked cylinder head is overheating. Remember that the cylinder head is made of metal, which expands and contracts depending on its temperature.
It’s not surprising then that overheating and the cycle of rapidly heating and cooling can cause the cylinder head to form cracks.
What’s worse is when the cylinder block and cylinder head are made from two different metals. For example, one is made of cast iron, while the other is aluminium.
With different metal types, the two parts will expand and contract at different rates. In this case, the lighter metal (aluminium) will likely crack first.
Indirect Causes: Cooling System Issues
Other problems indirectly related to a cylinder head can also cause it to crack. For example, a problem with your cooling system (say, lack of coolant) can lead to localised hotspots around your cylinder head.
That localised hotspot will expand faster than the rest of the cylinder head and cause cracks.
Can a Cracked Cylinder Head Be Repaired?
Regardless of the cause behind a cracked cylinder head, there is some good news. Yes, a cracked cylinder head can indeed be repaired. Of course, the degree in difficulty will depend on how many cracks you’re dealing with and how severe each one is.
So, when you want to repair or recondition a cylinder head, you have two approaches at your disposal: pinning and welding.
Let’s take a closer look at each method.
Pinning a Cracked Cylinder Head
Crack pinning (also known as crack stitching) is the most common and affordable approach to fixing a cracked cylinder head. This approach works for aluminium and cast iron and requires minimal tools and skills on the repairer’s part.
Holes are drilled on both sides of the crack to keep it from spreading. Then, overlapping pins will be installed along the crack to hold both sides firmly in place.
To perform this repair, all that’s needed is a drill, a guide fixture, and a tap.
Here, the size of the used pins will differ depending on how bad the crack is. For instance, more minor cracks require smaller pins, while larger cracks will require larger pins. Also, the pattern in which the pins are installed will differ depending on where the cracks are located.
Welding a Cracked Cylinder Head
As you might imagine, welding is a more advanced form of repair for a cracked cylinder head. For starters, you’ll need specialised equipment (like a welding equipment), and the repairer must have the necessary skills and experience to weld the cracked parts successfully.
Think of welding as the more ‘surgical’ repair option of the two.
There are various welding methods available for this repair, but we won't go into detail on that. Welding produces the same result: by filled the crack with molten metal, the integrity of the cylinder head is restored.
As we all know, the more complex the equipment and skills required for a car repair, the more expensive it’ll be.
So, what do you get for paying more money to choose welding over pinning? Well, simply put, welding eliminates the crack instead of just holding it together with pins. When the job is done, you’ll probably forget there ever was a crack in the first place (unlike pinning).
Even severely cracked cylinder heads with very little hope for a second chance at life can be restored through welding.
How Much Does It Cost to Repair a Cylinder Head?
Now, to the more crucial question: What’s the cost to repair a cylinder head? Well, it’s hard to throw out a specific price for cylinder head reconditioning or repair.
The truth is that when it comes to this type of repair, the workshop will look at several factors before giving you a quotation, such as:
- Your car’s make and model
- The severity of the damage (for instance, how big the crack is, and which part of the cylinder head is affected)
- Labour quality (i.e., some places charge more because their repairs have the skills and experience to do an excellent job)
- Labour charges
You can expect the charges to start at about $500. As mentioned above, that number can go up and down depending on several factors.
Here’s a pro tip for getting the best price possible: get three quotations from different repairers and choose the one that fits your needs best (Think: budget vs quality).
Is It Worth Repairing a Cracked Cylinder Head?
Another helpful question to ask: Should you bother with repairs, or wouldn’t it be smarter to just buy another one? After all, you can shop for a new or reconditioned cylinder head online with ease.
Well, again, think about that tip we gave you. Firstly, you should get at least three quotations from cylinder head repair providers. Then, once you know what the market will charge you for those repairs, you can compare that with the cost of a replacement cylinder head.
Depending on your situation, you might find that an affordable repair is all that’s needed. Or you might find that all of this is an excellent reason to go shopping for a brand-new cylinder head since your old one isn’t worth fixing.
Learn Something New Every Day!
To locate sellers of used or brand-new cylinder heads or mechanics and repairers near you, check out the directory at Carpart.com.au or browse what’s advertised at the Marketplace.
Alternatively, you also have the Part Finder to source your new cylinder head from suppliers across Australia. Request a part now, and we’ll connect you to reputable car part sellers near you!
By Ray Hasbollah