DIY Valve Guide Replacement Guide

1. Using a metal ruler, check the deviation from the plane of the surface of the block head. Limit value: 0.05 mm (gasket side); 0.03 mm from the collector side).

2. Check the combustion chambers, intake and exhaust ports and cylinder bore for cracks. If damage is found, replace the cylinder head.

Valve guides

3. Using a bore gauge, measure the inner diameter of the valve guide in several places along mutually perpendicular diameters. Nominal value: 6.500-6.015 mm.

4. Using a micrometer, measure the diameter of the valve stem in several places along mutually perpendicular diameters. Nominal value: 5.955-5.970 mm (inlet valve); 5.935-5.950 mm (exhaust valve).

5. Calculate the gap between the valve stem and the guide sleeve. Nominal value: 0.03

0.06 mm (inlet valve); 0.05

0.08 mm (exhaust valve). If the value obtained is greater than the nominal value, replace the valve and bushing.

Replacing the guide bushing

6. Using a suitable mandrel, press the guide sleeve out of the block head.

7. Ream out the mounting holes of the cylinder head in accordance with the repair dimensions of the bushings (see table).

8. Using a suitable mandrel, press in the guide bushing. The bushing should be pressed into place on the top side of the block head (see Fig. NA 2.085).

Attention: the intake and exhaust valve bushings have different lengths:

36.3-36.7 mm (intake valve); 40.841.2 mm (exhaust valve).

Repair dimensions of valve guides

size

9. After installing the bushings, insert the new valves and check the clearance between the bushing and the valve stem using a travel indicator while rocking the valve stem.

10. Check that the valve is seated correctly. If necessary, treat the locking surfaces of the valve seats.

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Why are guide bushings needed?

At the beginning and middle of the last century, car cylinder heads were made of cast iron, and the valves were simply inserted into precisely drilled holes. But subsequently, manufacturers abandoned cast iron heads due to their heavy weight and insufficient removal of excess heat, and they were replaced by lightweight cylinder heads made of aluminum alloys. These metals have excellent thermal conductivity, but have little resistance to wear from friction.

To solve the problem, a guide sleeve was invented - an intermediary between the soft alloy of the cylinder head and the steel valve stem, which constantly moves up and down during operation. Made of cast iron or special bronze, it is securely pressed into the cylinder head body, and the valve is inserted inside with minimal clearance.

The engine diagram shows the location of the guide bushings

The bushing itself is a hollow cylinder, made exactly to size for a specific car model. The outer surface is polished and smooth to the touch, and the inner surface has a spiral-shaped groove in the form of a thread. Motor oil moves along it, lubricating the valve axis and reducing friction. A shallow recess is made in the upper part of the guide part, into which a retaining ring is inserted.

On the left is the bushing for the exhaust valve, on the right is for the intake valve

Important point. The guide elements for the intake and exhaust groups of valves differ in design, although they may look the same in appearance (for example, parts for Russian VAZ 2108-09 cars). The difference is this: in the bushing for the exhaust tract, the oil groove is made along the entire length of the hole, and for the intake tract - only halfway. But products for the “classic” VAZ 2106 also differ in size; with the same diameter, the exhaust elements are longer than the inlet elements.

Bronze bushings for VAZ 2109 all look the same

Bushings perform the following functions:

• as the name implies, they direct the movement of the valve so that its plate is clearly aligned with the seat and fits tightly to it;
• take on the load from the friction force that occurs during the translational and reciprocal movement of the valve stem;
• the valve cup gets very hot in the combustion chamber, and the bushing transfers this heat to the aluminum alloy of the cylinder head;
• Thanks to a special groove, the part provides lubrication of rubbing surfaces.

Cast iron parts of VAZ 2106 - intake bushings are shorter than exhaust bushings

When the element is pressed into the cylinder head hole, its upper part of smaller diameter protrudes several millimeters above the surface. This is necessary to install an oil seal on it (also known as a valve seal), which prevents lubricant from the upper part of the engine from entering the combustion chamber through the inner hole of the bushing.

This is what the protruding part looks like where the oil seal is put on

General arrangement of cylinder head bushings

On modern cars, valve heads are made of special alloys.

Valve guides for VAZ 2106

On the VAZ 2109, for example, the guides are made of wear-resistant material and are pressed into the head at high temperatures, so changing them is quite difficult. But it is still necessary to carry out the replacement procedure, since the bushing, despite its strength, wears out over time, losing its tightness. The problem is especially acute for engines with a large number of valves.

Causes of parts failure and their consequences

A characteristic feature of the guide elements is that they do not fail at once, but wear out gradually. The lifespan of parts on budget cars ranges from 180 to 300 thousand km, and on more expensive foreign cars it can reach 1 million km. The wear process is influenced by several factors that can accelerate it:

• the quality of the motor oil used and the timeliness of its replacement;
• temperature conditions of the power unit, the more often the engine overheats, the faster the rubbing surfaces wear out;
• the quality of the fuel and combustible mixture, whose vapors penetrate into any leaks and contribute to the process of slow destruction of parts.

Carbon deposits on the rod destroy the bushing quite quickly

Note. The working life of all elements of the gas distribution mechanism is also affected by the serviceability of the power supply and ignition system. When, as a result of a malfunction, pops occur in the fuel or exhaust manifold, the lubricant between the valve-bushing pair is washed off with unburned gasoline, which is why the mechanism runs “dry” for several seconds.

A worn part is characterized by a “broken” internal hole, as a result of which the valve stem begins to move too freely in it, and then play appears. The rod warps during operation, and the plate does not fit well with the seat, the tightness of the interface is gradually lost. Gases escape from the combustion chamber into the mechanism, and oil enters from above, resulting in the formation of carbon deposits. It also accelerates wear, quickly rendering the part completely unusable.

Symptoms of wear

The main symptom of worn guide bushings is increased engine oil consumption. This is due to the fact that when the valve stroke is decentralized, the valve stem seals stop doing their job and engine oil enters the cylinders through the increased gap between the valve and the inner part of the bushing.

Signs of increased oil consumption due to worn bushings are as follows:

• blue smoke from the exhaust pipe;
• increased smoke from a running engine;
• carbon deposits on the spark plug electrode have a light fluffy appearance;
• presence of oil on the skirt or threads.

When do you need to change guides?

The main symptom indicating that the valve bushings have become unusable is increased engine oil consumption. When the rod has lateral free play (play), the valve stem seals are no longer able to prevent the penetration of lubricant into the cylinders from the upper engine compartment, where the camshaft is located. It flows into the increased gap between the valve stem and the inner diameter of the bushing and freely enters the combustion chamber.

Blue smoke coming out of the exhaust is a sign of oil combustion.

Signs of oil consumption due to problems with the guides are:

• bluish smoke from the exhaust pipe from escaping combustion products of lubricant that constantly enters the cylinders;
• the car practically does not lose in dynamics, but smokes a fair amount;
• light “fluffy” carbon deposits on the spark plug electrodes;
• liquid oil is observed on the skirts and threaded parts of the spark plugs.

Advice. By the carbon deposits on the spark plugs, you can determine the cylinder into which the largest amount of lubricant gets. This will be useful for performing diagnostics.

This is oil deposits on the spark plug.

Since oil can also penetrate into the chambers due to the fault of the cylinder-piston group, it is necessary to carry out diagnostics to accurately determine the malfunction. As an example, it is proposed to take the popular VAZ 2106 car:

1. Measure the compression in the cylinders. The goal is to ensure that the piston rings are in good technical condition.
2. Remove the valve cover, loosen the chain and unscrew the camshaft gear, first aligning the marks.
3. Dismantle the camshaft along with the bed and remove the rocker arms. Unlock the valve springs of the cylinder whose spark plug is more heavily covered with carbon deposits.
4. Carefully remove the oil seal and try to rock the rod sideways with your hand, while moving it up and down.

To feel the play, the valve must be pulled out by the stem and rocked to the sides

If there is play, you can safely continue disassembly, since to replace the bushings you need to remove the cylinder head. If you have no doubts, check the other valves, the picture should be approximately the same.

Tools and materials

Replacement of guide bushings is carried out using the following tools:

• hammer;
• sweeps at 8.022 and 8.028;
• mandrel for pressing out and pressing in bushings.

The bushings are changed using a stepped mandrel - a brass or bronze tool. It rests against the guide sleeve, after which it is knocked out with a hammer blow. This method of pressing out does not harm the cylinder head as much as using a regular hammer and chisel. A special puller is used not only to remove bushings, but also to replace them.

Stepped mandrel used for pressing out VAZ 2106 guide bushings

The best tool for replacing guide bushings is a push-out puller. Such devices allow you to remove valve bushings without damaging the seating plane on the cylinder head. The presence of this tool allows you to avoid scoring and other cylinder head defects that may appear when using a mandrel and hammer.

Puller-extruder for guide bushings VAZ 2106 - universal tool

The procedure for replacing guide valves on a VAZ 2106

The whole procedure is divided into several stages:

1. Preparation of tools.
2. Partial disassembly of the engine, namely, removal of the cylinder head.
3. Selection and purchase of new parts.
4. Dismantling worn elements and pressing in new ones.
5. Reassembling and starting the engine.

The first step is to disconnect the battery from the on-board network

Advice. It is worth following exactly this sequence of actions - first disassembling the engine, and then purchasing spare parts. The dissection will show you exactly what parts you need. If you recently changed the valves (5-10 thousand km ago), then you need to pull them out to try them on with the new bushings in the store. The old valve group will have to be replaced.

Preparing the necessary tools

To disassemble and replace the guides, you will need:

• standard set of open-end and ring wrenches;
• a set of sockets with a powerful wrench and ratchet;
• a torque wrench for tightening the cylinder head bolts and camshaft nuts during assembly;
• screwdrivers, pliers;
• 36 mm wrench for manual rotation of the crankshaft;
• mount;
• puller for unlocking valves;
• heavy hammer;
• mandrel for knocking out and pressing in bushings;
• 8.025 mm reamer with knob;
• container and hose for emptying the cooling system;
• rags.

You can’t do without a ratchet wrench and sockets when removing the cylinder head.

The mandrel for working with guides is a steel rod, the end of which is machined to fit the inner diameter of the bushing. The second part of the mandrel is a nozzle for pressing, the size of which is adjusted to the wide outer part of the part (the so-called cap), since it is impossible to hit the end. The kit can be ordered from a turner or purchased ready-made; it is inexpensive.

The mandrel for knocking out and seating bushings can be machined according to the drawing

Advice. In the process of replacing the guides, you will have to re-grind the valves, or even trim the seats. This work requires a special tool and appropriate skills, so it is better to entrust the operation to a master. In addition, the purchase of devices for cutting and lapping will reduce to zero all the benefits of repairing the cylinder head with your own hands.

This is a scan used on the cylinder head of VAZ 2101-07 cars

A reamer is a bench tool designed for precise adjustment of the internal diameters of holes. In this case, it is necessary to rotate the inner part of the bushing under the valve stem with minimal clearance.

Removing the cylinder head and old bushings

This stage is the most labor-intensive and time-consuming; it begins with disconnecting the battery and emptying the water jacket of the engine (there is no need to drain the liquid from the radiator). Perform further operations in this order:

1. Disconnect the starter cable, gasoline hose and accelerator drive, then remove the air filter housing and carburetor.
2. Unscrew the valve cover and align the notch on the crankshaft pulley with the long notch on the block. Disconnect the wires from the spark plugs and remove the distributor, remembering the position of the slider. Remove the wire from the temperature sensor.
3. Loosen the chain by unscrewing the tensioner, then unlock the camshaft gear nut and unscrew it. Remove the gear and secure the chain so that it does not fall inside the block. Unscrew the nuts securing the camshaft bed and remove it from the studs.
4. Disconnect all cooling system pipes and exhaust pipe “pants” from the cylinder head.
5. Loosen the 11 cylinder head bolts in random order and remove them. Using both hands, lift the cylinder head and remove it along with the manifolds.

Removing the filter housing

Advice. Immediately after dismantling the head, clean the block of the old gasket and cover it with a clean cloth so that dirt does not accidentally get inside the cylinders.

Place the removed cylinder head conveniently on the table and remove the springs with the rocker arms (it is advisable not to mix them up), then use a puller to unlock the valves and pull them out. At the same time, do not lose the “crackers” - small half-cylinders inserted into the slot of the rod. Then turn the head over with the combustion chambers facing up, place wooden blocks along the edges and knock out all the bushings with a mandrel. Strike with medium force, clearly and accurately. At the end, clean and thoroughly wipe the entire cylinder head from carbon deposits and deposits.

The carburetor must be removed from the manifold so that it does not interfere

Recommendation. Take this opportunity to inspect the disassembled engine for other faults in order to eliminate them immediately. Involve a mechanic - a motor mechanic with a device - a bore gauge, so that he can check the output in the cylinders and advise you on all issues. This is important if you are disassembling the VAZ 2106 power unit for the first time.

It is important to align the marks before disassembling

Photo instructions for removing the cylinder head

To get to the camshaft, you need to dismantle the valve cover. Removing the distributor. The camshaft gear must be unscrewed and removed without disturbing the position of the marks. After unlocking, the springs can be easily removed. The cylinder head must be carefully removed with both hands. To remove the valves, you need to use a puller to unlock the cylinder head springs in disassembled form. Removing the camshaft housing. Disconnecting the wire from the temperature sensor From the cylinder head, you need to remove all the pipes of the cooling system. The bushing is knocked out with a hammer through a mandrel. Removing the rocker arm springs (rockers).

How to dismantle the cylinder head of a VAZ 2106 - video

Selection of new parts

Guide bushings for the "six" engine can be purchased in two versions - cast iron or bronze. When choosing, you should adhere to the following recommendations:

1. If you have a normal driving style and are not into car tuning, there is no point in installing bronze products. Buy inexpensive cast iron guides and they will last quite a long time.
2. It is better to install bronze parts together with lightweight chrome-plated valves (for example, from the AMP brand).
3. Considering the price of cast iron products and your first experience of replacing them, it is recommended to purchase 2 sets of parts. The reason is the fragility of the material, which can accidentally crack if handled improperly.
4. Select the bushings in such a way that the valves are inserted into them with difficulty or do not fit at all. Do not take products with incorrect holes where the rod fits freely.
5. If after disassembly you find that one or more bushings are spinning or dangling in the cylinder head sockets, you need to select repair products. Their outer diameter is 0.05-0.1 mm larger than the standard one, which will allow such parts to fit into broken holes in the cylinder head. Here it is worth using measuring instruments - a micrometer and a bore gauge.

Advice. Do not listen to assurances that bronze bushings resist wear better than cast iron ones, this is not true. Cast iron is much harder than most metals, including bronze, it just transfers heat less well. Hence the conclusion: both parts are good, but they must be used for their intended purpose.

It is also worth purchasing a new valve group (if it has not been changed recently), gaskets for the cylinder head and various pipes, and 1-2 liters of antifreeze for topping up. Buy the rest of the parts based on the results of the previous troubleshooting.

Fitting bushings and reassembling

To press the guides into the sockets, turn the cylinder head over with the combustion chambers facing down. Then place the retaining rings on the elements, pulling them from the top end. If you start putting the ring on from the bottom, be sure to leave deep grooves on the surface where oil can subsequently leak.

Important! Before planting, lubricate the outer surface of the parts with a thin layer of engine oil.

The new bushing is driven all the way through the spacer

To press fit, insert the end of the first bushing into the hole, put the nozzle on the mandrel and attach it to the wide part of the part. Using precise blows of a hammer on the spacer, drive the bushing in until it stops, which is characterized by a change in the sound of the blows (a slight ringing will appear). Hit with medium force so as not to crack the cast iron. Repeat the action with all the elements, and if one of them breaks, take a spare one.

Reference. You can often hear recommendations that the cylinder head should be heated in a bucket of water, and the bushings should be placed in the freezer before driving. These activities really make pressing easier, but take a lot of time. Any knowledgeable mechanic will tell you that fitting cast iron into an aluminum alloy with an interference fit of 0.04-0.06 mm can be easily done without any heating.

The bushing holes should be driven through with a reamer

After pressing is completed, you need to drive the inner diameter of the bushings with a reamer so that the valve stem slides in it with minimal clearance. The operation is performed as follows: secure the tetrahedral end of the reamer in the driver, lubricate the working part with engine oil, insert it into the hole and rotate clockwise. The tool must go along the entire length of the part. Now all that remains is to install and grind the valves, which is recommended to be entrusted to a specialist. Then reassemble the engine in reverse order, but taking into account the key points:

1. If you want to improve the tightness of the gasket between the head and the block, treat it with a thin layer of graphite lubricant. High temperature sealants cannot be used.
2. Tighten the 10 main cylinder head mounting bolts with a torque wrench in 2 steps in the sequence shown in the diagram. The first time tighten them to a torque of 41 Nm, the second time - 118 Nm. The eleventh bolt of a smaller size is tightened at a time with a torque of 39 Nm.
3. The camshaft bed is also pulled according to the scheme, maintaining a torque of 22 Nm.
4. The gear and chain must be installed so that the round mark on the sprocket coincides with the boss on the camshaft housing. You aligned the marks on the crankshaft before disassembling, check them.
5. Do not forget to adjust the gaps between the rocker arms of the valve group and the camshaft cams (its value should be 0.15 mm).
6. When installing the distributor, restore the original position of the slider so as not to disable the ignition.

Cylinder head bolt tightening diagram

Advice from experienced people. After tightening the cylinder head bolts, old craftsmen often let the engine sit for 12-24 hours, and then tightened the head again. If you have time, follow this recommendation; in a day you will see for yourself that the nodes have “settled” and the bolts have loosened a little.

Procedure for tightening the camshaft nuts

After completing assembly and filling with antifreeze, start the engine, warm it up and rotate the distributor housing to set the optimal ignition timing.

Aligning the round mark on the gear with the boss on the body

Replacement process

As mentioned above, a special attachment is required to remove and install the guides. Let's look at what it is and how to use it.

Description of the tutorial

The mandrel for removing and installing the guide consists of two parts. The first part is a rod of a certain length, machined on a lathe and having different diameters in certain places. The largest diameter of the rod occupies its main length and is 18 mm. The rod is held by hand by this part, and it limits the rod from slipping to the other side when removing the bushing, which will protect the surface of the block head from being hit with a hammer. The diameter of the second part of the rod is equal to the diameter of the sleeve. The length of this part is equal to the depth of the hole in which the sleeve is located. The third part of the stem is the shortest - its diameter corresponds to the internal diameter of the valve stem (the diameter of the inner surface of the guide). Its purpose is to ensure that when knocking out the bushing, the direction of the rod strictly corresponds to the direction of the bushing and does not create a distortion of the rod when hitting it with a hammer.

The second part of the rod is similar to a socket head. It is distinguished from a socket head by the absence of edges inside (a cylindrical hole with a diameter and length equal to the diameter and length of the upper part of the guide). In the upper part of the head there is a hole with a diameter equal to the inner diameter of the sleeve and the outer size of the rod on the working side. As can be seen from the description of the mandrel, finding a replacement for it using available materials is not so difficult. To do this, at a minimum, you will need a cylindrical rod of a convenient length, the diameter of which on one side is equal to the outer diameter of the sleeve. As an attachment, you can use an old oil pump rod from a VAZ, after grinding off the gear.

To install the guide in place, use a socket of the appropriate diameter or a suitable hollow tube. Further in the text the terms “mandrel”, “rod”, “head” will be used, implying both a special mandrel and suitable available means.

The process of removing a worn guide and installing a new one

To remove the bushing, turn the cylinder head over with the working part facing up. Next, take the stem, insert it into the valve hole and carefully press it out with a hammer.

In this process, the accuracy of the blow is important. If you hit the surface of the cylinder head with a hammer, this will disrupt the plane of the cylinder head. To knock out the bushing, the blow must be strong, and for this it is better to use a heavy hammer. To install a new bushing, place the cylinder head on the surface in the position in which it is placed on the engine. Then take the new bushing, coat the outer surface with oil and install it in the desired hole.

Next, put the head on it and insert the rod. Gently hitting the top of the rod with a hammer, press the bushing guide into place. When installing, pay attention that the selected means do not touch the top of the oil seal seat (marked with arrow 1), since upon impact the seat will be deformed or a piece will break off from it. The head should rest against the base of the oil seal seat (marked with arrow 2).

There are no problems with removing and installing the guide bushing. This is a simple procedure that requires certain knowledge, accuracy and precision when working.

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