On an overhead cam engine the valves don't grow loud over time, signaling the need for adjustment as they do on older cam in block engines. Rather OHC valves grow silent as proper clearances disappears with wear.
The sound of a noisy valve that goes away when an OHC engine warms up is often the sound of a normal valve closing. The noise can be heard through an exhaust manifold leak at the manifold to head joint caused by a loose manifold stud, often the number 5 stud, a burnt out manifold gasket, or both. The leak closes as the cast iron manifold heats up and expands.
Loud Valve, How to Adjust & Oil
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rridge
- Posts: 162
- Joined: Thu Aug 10, 2006 11:59 am
- Your car is a: 1981 Turbo Spider
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SteinOnkel
- Posts: 1000
- Joined: Tue Feb 19, 2019 9:31 pm
- Your car is a: 1978 124 Spider 1800
Re: Loud Valve, How to Adjust & Oil
You know...you might be right. But it sounds so metallic hmmm.
We did have to mess with the header a fair bit in the last few months. It likes to leak at the donut (4-1 header) and the studs...well, we don't talk about the studs. The DPO took the most ham-fisted approach to those poor things. Most of the threads are stripped out. On the intake side as well. I won't have a change to fix that properly until I pull the head.
Cheers
Steiny
We did have to mess with the header a fair bit in the last few months. It likes to leak at the donut (4-1 header) and the studs...well, we don't talk about the studs. The DPO took the most ham-fisted approach to those poor things. Most of the threads are stripped out. On the intake side as well. I won't have a change to fix that properly until I pull the head.
Cheers
Steiny