1.8L sounding strange

dcolletti · 07-10-1999, 12:02 PM

I have a 1.8L carburated 914 that sounds like a Brigss & Stratton engine from a lawn mower. I removed the spark wire from cylinder #4 to see where the sound was coming from and that was the cylinder. What could the problem be?

aporsche914 · 07-10-1999, 12:51 PM

its an exhaust leak at the cylinder head due to stripped threads in the aluminum head, and the HE isnt sealing, or, if youre lucky, which i doubt, you just need a new copper gasket in between the HE and the head..but 99% chance its a stripped threads

John Rogers · 07-10-1999, 07:57 PM

If one of the threads has stripped out, I would recommend doing all four. There are over size studs available and you can get thread inserts to install and you will never have another leak. Of course it is a little messy laying under the car and redoing the holes....but it can be done in car without dropping the engine.

dcolletti · 07-11-1999, 05:04 AM

I have never touched the cylinder heads before so why would it be a stripped head bolt? I am thinking that it could be a burnt value. The noise only comes from the #4 cylinder.

aporsche914 · 07-11-1999, 11:56 AM

it doesnt matter if you never touched them..its probaly something that happened before..a burnt exhaust valve wouldnt make that noise, it would just cause you to lose compression and power on the cylinder, not make a lawn mower sound.., and yes..the noise only comes from one cylinder when you have a stripped thread, the noise comes from the cylinder that has the stripped thread..

[This message has been edited by aporsche914 (edited 07-11-1999).]

JP Noonan · 07-11-1999, 02:47 PM

If your 1.8L had an air pump at one time see if the air injection tube that screws into the head is loose. My 75 2.0L had this proplem.

Also if it is indeed a leak at the head, FIX IT NOW!!! letting it leak WILL ruin the head. The motor I got from a PO had a leak for a couple of months and there were large pieces of alum missing where the HE meets the head. Also make sure you have a mufler bracket. About not touching them, every time you heat up the car and let it cool off you are "touching it" with thermal expansion.

Also check the spark plug, sometimes (only seen it twice) the porsulin comes loose from the ground of the plug. Both times though it blew the plug clean out of the hole. Also check that the spark plug hole isn't striped.