TBITrucker

Help!

The car is an 88 ' maro with the 305 L03 TBI.

I have the dreaded idle hunting problem. It also idles rough too (sorta chugs a little)

I have been chasing down these problems for months and I am stumped.

Today while doing some vacuum testing I noticed something real strange...

After the car has been shut off there is a clacking or knocking type sound coming from under the valve cover on the passanger side!
It makes these noises at random intervals for up to two minutes after I shut off the car. This only happens if the car was good and warmed up before turning it off.
It seems heat related?
What the heck could it be? bad lifters or bad valves or spings? bad head gasket?

Could it have something to do with my rough idle or the Idle hunting problems? Or is it just a neat new way for my car to get even more of my attention?!

Any Ideas?

AJ_92RS

It's one of the hamsters trying to get out!!! Those damn things!!!

:sillylol:

Might be a broken valve spring. Pull the covers off and take a look. That would also explain the erratic idle/running.

TBITrucker

A Bad valve spring? I will take the covers off Sat. and check that out.

I have always suspected something is wrong under there because the engine chugs a little. It acts like it has a miss.
It also has stinkey rich smelling exhaust. (all the plugs look normal though)
Also the exhaust is always visible even in the summer and even when the engine has been running a while.
If you watch the exhaust there is one burst of exhaust that puffs out of the tailpipe further then the rest of the exhaust cloud, and when it shoots out your hear a faint chugging sound.

Lets hope it is a 3$ spring and not bad lifters.

steve8586iroc

Try running a compression check on it too.

Steve

TBITrucker

I agree on the compression test also
I had one "done" by a nearby shop but I did not trust their findings. I was there to get a flat tire patched and I had them do the test as long as I was there. I walked across the street to Tim Hortons for a coffee and a donut and when I came back they were done! They said it tested OK. But when I asked them for the readings they said oops! we forgot to write them down. I don't think they even tested it. How could they test all 8 in less than 5 minutes? These guys couldent even get out of there own way in ten minutes!

I did not pay them what they asked for I Only paid for the flat repair (wich by the way leaked and I had to go and get it fixed at Goodyear.)and it got real heated up for a while then the one guy just said OK forget it and laughed like he new he was caught BS'in me.

I bought a tester at Auto Zone and I plan on testing it myself I figured I should have a Guage around anyway.

Frik92RS

"When you think its a major problem it's usually something small and stupid."

Try checking the PCV valve, if it's clogged or stuck it can affect idle performance, and the sounds you hear might be it rattling in and out as the oil pressure changes in the oil pan as the motor cools off.

Hope that helps!

TBITrucker

I gave it a try. I cleaned out the pcv valve with carb cleaner warmed up the engine real good and it still made the noises. I pulled the pcv right out and the noises continued. When I put my hand on top of the rocker cover I can actually feel the clunk when the noise occurs. It realy seems like it is coming from inside the engine or cylender head. I cant figure it out and now to top it off ive got a huge oil leak! I cant see where it is coming from so I will have to get it up on the ramps later today. Maybee they are all related?

jasonbennett

is it like a ticking sound? it is probably the heat shields ticking fro beng hot and now they are cooling off. it's not internal. it's just everything cooling off.

TBITrucker

It is not the heatshields. I dont have any! The previous owner ripped them off because he said they got in the way of putting in spark plugs! The worst part is that he just ripped them out and there was still bits of sharp sheet metal stiking out from the places were they had been fastened on. It took me a while to get those peices off.

Thank *** for ViseGrips!

I bought one of those mechanics stethoscopes and listened around as the noises were going on. It realy seems to be coming from inside the cyl. head. It sounds like somthing is springing up and hitting something. You can actually feel it ! It is almoast like there is metal banging on metal.

Can a lifter get bound up and then spring up against the cam or the pushrod? or spring up and move around in its bore?

copperhead110

could it just be dieseling? BTW, a long screw driver held to the engine and to your ear is a cheap stethoscope. I'm sure it has lower sound quality but it might be adequate. (Remember hold the handle to your ear

Let us know what you find out.

RegaPlanet

take the valve cover off and observe... I'm gonna go with the suggestion that it's a vavle spring

TBITrucker

OK I did a compression test and I think It is OK....But the instructions said to do it with the engine warmed up to regular operating temp. Well it was when I started but by the time I got done it had cooled off quite a bit because I pulled all the plugs then tested each cyl and then squirted in some oil and tested again. So should I test it again? Everthing was in spec with my Haynes manual.

I took off the valve covers and used a reading glass to look at the valve springs. They look OK but I can not see the whole coil due to the rocker arm. Should I disassemble each one to inspect it? or would a bad spring have been real noticable?

The engine is not diesaling its definatly off and not spinning at all.

Someone said I may have a bad oil pump and the engine is getting to hot and there is pressure built up inside causing the noises. (and my oil leak that just showed up a few days ago but after this noise problem) Is that possible? Ive never heard of anything like that before. Although my factory guage shows my oil pressure at 10 psi at idle and 20 psi at speed and it fluctuates all over between 5 and 25 psi could I have a bad oil pump?

I replaced the sender about 4 months ago but it did not change anything. The guage has always done this since I got it, the last owner said it did the same thing to her also.

Frik92RS

It should read much higer than that. ine reads at 60 when I start the car and then goes down to between 20-30 when idling warm, then back up to 50 when I hit it.