What is integral valve guide?

A valve guide is a cylindrical piece of metal, pressed or integrally cast into the cylinder head, with the valve reciprocating inside it. Guides also serve to conduct heat from the combustion process out from the exhaust valve and into the cylinder head where it may be taken up by the cooling system.

What are the two types of valve guides?

Material choices for guides are down to two distinct types – cast iron and bronze.

What are the three types of valve guide seals?

Either way, the engine is going to have problems.

• There are three types of valve guide seals: umbrella, positive, and O-ring [ see Figure 4 ].
• The umbrella seal, used on many older engines, fits snugly over the valve stem.
• The O-ring seal was used on many millions of older General Motors engines.

What is integral valve seat?

Seats of a Gate valve Integral seats provide a seat of the same material of construction as the valve body while the pressed-in or threaded-in seats permit variation. Rings with hard facings may be supplied for the application where they are required.

What is the main function of valve guides?

Valve guides play a critical role in the function of today’s internal combustion engines. They are responsible for the proper function and alignment of engine valves which are required for introducing air for combustion or eliminating the post-combustion exhaust gases from the cylinder.

What happens when valve guides are worn?

Worn guides can also contribute to valve breakage. The guides support and center the valves as they open and close. A worn guide will allow the valve to, wobble slightly as it opens. This will cause it to drift off-center with respect to the seat.

What kind of head can use an integral valve seat?

Like valve guides, there are two types of valve seats – integral and insert. Integral seats are part of the casting. Insert seats are pressed into the head and are always used in aluminum cylinder heads. Most pre-1978 integral seats are soft cast iron.

What is the purpose of valve seals?

Valve stem seals prevent oil from contaminating the air/fuel mixture in the engine’s combustion chamber. They also prevent intake and exhaust gases from contaminating the oil in the cylinder head and the rest of the engine.

How are valve guides lubricated?

Different than other seals in the engine, valve stem seals play an important role in lubrication. Valve stem seals allow a controlled amount of oil to lubricate the valve stem as it moves in the valve guide. The amount of oil that passes by the valve stem seal must be precisely controlled.

What is wedge in valve?

The purpose of the wedge shape is to introduce a high supplementary seating load that enables metal-sealed wedge gate valves to seal against not only high but also low fluid pressure. The wedge shape also results in a seal on both sides of the gate.

Should I replace my valve guides?

If the clearance is too large or the valve guides are worn out-oftrue, conical or flared, they must be replaced. For valves with a skirt diameter of less than 8 mm in particular, knocked out valve guides have a big impact.

Should I replace valve guides?

How are the valve guides kept in place?

The valve guides are kept in place in the cylinder head with a press fit. The valve guides supplied by Motorservice are already fully machined on the inside diameter. Due to the press-in procedure, the valve guides might be slightly constricted radially on the inside diameter.

Can a broken integral valve head be salvaged?

In cases where the original integral guide is too badly worn or damaged to accept an oversize valve or a guide liner, some heads may be salvaged by installing a whole new guide. When used valves are salvaged and the stems are reground, grinding removes the chrome flashing.

How do you recondition cast iron valve guides?

On cast iron heads with integral guides, the most popular methods of reconditioning guides is to ream out the guides to accept valves with oversized or rechromed stems, or to ream out the guides and install guide liners.

What should I look for when replacing valves?

When replacing valves, it is very important to check the valve guides too. Consequential damage to valves can often be caused by old and worn valve guides. Also learn about standard values for valve guide clearance. Worn, bent or burnt through valves are replaced.