How To Check Valve Guides – The Easy Way To Do This Job
August 22, 2021If you have leaky valves one of the things that you need to consider checking is the valve guides. So, how to check the valve guides? Well, checking the valve guides is not a simple task and will involve some work.
- What Are Valve Guides?
- What They Do?
- Types Of Valve Guides
- Do They Need To Be Replaced?
- What Causes Them To Wear?
- Symptoms Of Bad Valve Guides
- Checking The Valve Guides?
- How To Replace Valve Guides
- Conclusion
Valve guides know to leak and cause trouble. If they are bad, they get replaced along with the valve seals and the valves altogether. In order to make sure that your car will work properly again. This is the case because if you replace only one part the valve may leak again if one of the parts that were not replaced is damaged.
Valve guides are just pieces of the puzzle and they need to be in check in order to prevent leaky valves and protentional engine hazards.
This work is a tedious process and may require some expertise, although it’s not that complicated to do. You only need specific tools for this job and we are going to discuss them in this article.
In this article, we are going to see first what valve guides really are and what they do, which is their function, the two typed of valve guides. We will discover what happens when the valve guides are worn and also how to check valve guides. And finally, we are going to cover a small DIY chapter on how to replace the valve guides. So, if you are interested to learn more, follow along.
What Are Valve Guides?
A valve guide is a component in every combustion engine. Valve guides are mounted on the engine head. They have a cylindrical shape structure and are made out of bronze in most cases.
What Does A Valve Guide Do?
As their name says they guide the valve. The valves are inserted in these cylindrical guides. The guides make sure that they seat the valves properly on the head. Tolerances are low when it comes to the valve stem and the valve guide and they shouldn’t be more than a couple of micrometers between the valve guide and the valve stem. The clearance between the valve stem and the valve guide is between .002’’ and .004’’ for the exhaust and .001’’ to .003’’ for the intake. A play of .017’’ is acceptable, everything above that is considered loose and needs replacing.
Above the valve guide is a valve seal that makes sure that no oil goes inside of the combustion chamber. Usually, the valve guides, and the valve seals wear off and increase these tolerances, making the oil spill along and drip inside the cylinder.
These oil leaks can cause many issues like carbon buildup, low compression, loss of power, check engine light, etc. We are going to discuss the symptoms of bad valve guides in one of the next chapters.
Valve Guide Types
There are two types of valve guides. Depending much on the material that they are fabricated. Most of the valve guides come made out of bronze, some of the guides are made out of cast iron.
You can recognize the bronze guides by their yellowish color, the cast iron valve guides are usually silver in color.
Do Valve Guides Need To Be Replaced?
Valve guides are recommended to be replaced if you are doing a full valve job. By a full valve job, we mean replacing all the valves and seals. When you are replacing the seals and the valves, it is also useful to replace the guides as well. In the end, we are going to learn how to check valve guides and also how to replace valve guides.
Because valve guides are also parts that wear off with time and can make the seals not seal properly and cause leaks. If they leak you will have to do the job again, and this is valuable time and money spending that you want to avoid. Especially for parts that are dirt cheap and readily available.
The best advice is to replace the valve guides altogether and never worry in the future if some of these valve guides are going to fail on your engine head and cause an oil leak into the cylinder.
What Causes Valve Guides Wear?
There is constant friction between the valve guide and the valve stem. This friction causes the valve to wear. Wear is more common in engines that are not regularly maintained.
Many engines are not well maintained and these parts wear off properly. Also, the heat is one of the factors why the valve guides fail. The valve seals that are on the top and make the valve stem to seal with the valve guide are made out of rubber.
With time this rubber becomes brittle and causes oil to get inside of the valve guides. This oil then burns inside the combustion chamber and creates more head and carbon buildup. Making the valve stem to be more in contact with the valve guide and as the friction increases the bronze is starting to lose its volume. In the end, we are going to learn how to check valve guides.
Another thing that causes the guides to wear are changes in the engine that occur over time and the load that is applied to it.
What Happens When Valve Guides Are Worn?
When valve guides are worn the valve stems start to wobble and a play inside is developed. This play increases the friction and causes even more play because the materials are rubbing. They can also cause the valve seals to fail and oil to start dripping inside the valves.
This oil will soon get inside your engine and will cause many different symptoms that will occur to your engine like blue smoke, carbon buildup inside the cylinder and loss of power, and loss of compression.
Symptoms Of Bad Valve Guides
When valve guides go bad, they can develop a number of symptoms. All these symptoms are probably going to affect your driving quality in one way or another. When you see one of these symptoms it is important to check your engine and give it a good and thorough inspection at the mechanic’s shop or if you want you can do it DIY, but it will involve some skill, we are going to explain later how to check the valve guides in detail.
1. Noise From The Engine
If you carefully try to listen to the work on your engine you will instantly hear a ticking sound if your valves are not working properly. If the sound comes from the head, it is a clear giveaway that something inside is not right and needs to be taken care of.
2. Loss Of Power
Loss of power is another symptom when the valve guides and valve seals go bad. The valves will not seal properly and some of the compression will go away from your engine and will not bring the desired power numbers.
3. Blue Smoke
Blue smoke is also one of the symptoms when valve guides go bad. This happens because the oil that is used to lubricate the engine, is starting to find its way into the combustion chamber. Then the oil is starting to burn, and the car starts to develop bluish smoke from the exhaust. This blue smoke means that your engine is in danger and needs to be checked.
4. Loss Of Compression
Loss of compression is another symptom of bad valve guides. As we mentioned above when we have discussed the loss of power symptom. Losing power is a consequence of low compression. The less compression inside of the engine the less power the car will make. Your valves are probably not sealing properly and cause the engine to lose compression.
5. Oil Consumption
Oil consumption is the most frequent symptom when you have bad valve guides, bad valve seals, or bad valve stems. The oil is leaking inside of the combustion chamber and it starts burning. This will reduce your oil level and you will frequently have to fill up the oil. This is important because you don’t want to leave your car dry of oil. In this case, the engine will seize and stop working.
How To Check Valve Guides?
In order to check the valve guides, you will have to do some work on your engine. Much of the components need to be removed in order to get to the engine head and the guides.
These components include the intake manifold, fuel lines valve cover, and rocker arms. Everything needs to come out in order for you to have the working space to loosen the head studs and remove them from the engine.
After you removed the head, you will need to remove the springs and valves. You will need a special tool for this in order to release the stress from the spring and carefully remove it. First, you need to apply pressure on the spring and remove the spring keeper, then with the tool to relieve the stress. This needs to be done carefully to prevent the spring to pop out.
Then after you removed the valve, you can start measuring, and for this, you will need a special valve guide measuring tool. We will attach a video on how to check valve guides in order to have a clear understanding of how the procedure is done the proper way.
Also, the recommended amount of play between the valve stem and the valve guide is around .017’’. But the recommended tolerances are between .003’’ to .004’’.
How To Replace Valve Guides DIY?
Replacing valve guides is a fairly simple process.
The first thing to do is to make a proper working environment. You need to pull out the head from the engine and move it on your workbench.
Then you will need to get a valve guide removal tool. These tools are fairly cheap. Even if you don’t have one you can just fabricate one very easily. You only need one long nut, a small pipe, and a few washers.
Bolt the tool and start applying force by screwing the top bolt. Then the valve guide should come off pretty easy. With this tool, you can also install the new valve guide. A lot of force is needed to press the guide into place.
After you finished this work then it’s time to reassemble the head. When torquing the rocker arms don’t forget to adjust the valves. This is something that we are going to discuss in a future article.
Conclusion
In this article, we have covered a lot and learned what are valve guides and their function inside the engine. From what materials they are made and how they can be differentiated.
We also covered the main symptoms when valve guides are going bad. These symptoms are as we said, blue smoke, loss of compression, oil consumption.
Then we discussed how you can measure them with a proper valve guide measuring tool. And finally, we learned how these valve guides are replaced the proper way.
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