My engine valves aren't getting enough clearance. New engine or is it fixable?

Question

Its a 1986 Corolla with a stock engine. friend said the valves arent getting enough clearance but didnt know why. Any ideas?

Answer 1

your valves are out of adjustment, get a haynes manual or take it to a shop.

Answer 2

This is an interesting question...

The only clearance the valves need are the space they share with the pistons... it's called an interference engine. The valves share the same space with the pistons. If they enter that same space, they collide and all is lost. Literally.

The timing belt keeps the valves and the pistons in time so they don't meet in the middle and crash. If the timing belt skips a tooth, the timing between the valves and the pistons changes and the space may decrease but for sure the engine won't run as good. In fact, the engine can run really rough when the belt jumps only one tooth if it runs at all.

If the valves came into contact with the pistons while the engine was running, then they are most likely bent and may have caused damage to the pistons too. The only answer is to retime the engine (old belt is fine for diagnostic work) and see if you can develop compression without starting the engine. If you can't, the valves, at least, are damaged and you are talking of big $ to fix. A whole junkyard engine would be cheaper and easier to swap out.

You need a manual and a compression gauge.

Good luck... this one's a big one to tackle.

Answer 3

Well...anything is "fixable". But is it worth it? Are you SURE you're friend knows this is true? How would he know anyway, unless he actually WORKED on the car. And if he DID work on the car, he would have fixed it then, as it is an easy fix to adjust the valve clearance.

I suspect He is just making an educated guess.. You are only telling us what HE said, instead of the symptoms that YOU experience. So can't help much. You telll us the symptoms, not what some friend said was the answer. This is Yahoo answers, you know.

A car that old wears out. Just run it until it dies, which it will do. Then buy a newer used car. Don't throw good money after bad.

Answer 4

I don't have a manual with this specific car, however there is always some way to "adjust the clearance". If this is an overhead cam car, - with the camshaft running in bearings installed right in the head-casting, - there are proably discs under the rocker arms, (or cam lobes) that push the valves down to open. These discs can be removed and thinner ones put in , - or they can be ground down with a "mill". You merely "gauge the clearance, look in the book (manual) and see what they are supposed to be, - then put ones the right thickness back in place to leave the proper space to have right "clearance"!

There are radical things you can do to get clearance, if there is really no adjustment left (like worn out rocker arms or something like that), but you want to get a good experienced mechanic to do this for you - it is not a good place to experiment (if you don't know what you are doing)!

It is also possible to remove the head only, and replace severely worn parts to make everything perform as new, - (it will cost about 1/3 - or less than an engine overhaul).

Answer 5

I know why. Common problem on the Toyota aluminum heads. You need to have the valve seats checked, one of them probably is cracked. Or if the engine has been rebuilt or the cylinder head replaced, the valve may be compressing further and further into the head, causing a valve adjustment problem. The head material is soft on the Toyota, and if you have a valve that will not adjust correctly, it is probably pulled the seat into the head further than it is supposed to be. I have seen this before on the pickup engines. Have it checked, a new head may be needed.

Answer 6

How did your friend ascertain that, You have to take off the valve
cover and measure the gap with a feeler gauge. Did he do that or did he just guess?


There are two basic kind of lifters that lift the valves.
Hydraulic (use oil pressure kind of) and
mechanical... the mechanical kind has a big nut on top of the rocker arms they are used to adjust clearance.......

BUT they do not normally tighten themselves with out a humans help..................... Get the haynes or chilton manual for your particular car and read up BEFORE you adjust anything.....

Answer 7

Is the engine a mechanical lifter engine ? It will have an adjustment if it is. Check out a repair manual . Whatever the problem is I seriously doubt you will need a new engine

Answer 8

Don't put money into a 20 year old economy car. Drive it until something serious happens, then get a newer vehicle.

Answer 9

Your friend is a buffoon with little or no knowledge. How would he know?