blazer427X3

I bought this car late in June of 09 and have put just over 5,000 miles on it. The only thing I've done were to put new tires on it and do routine maintainance.

Engine mods are: Texas Speed 2.55 heads, Texas Speed 233/239,595/603-112 LSA cam, Comp. Cams valve springs and rockers, Ported T.B., BBK Intake, Vararam, FLP Long tubes, no cats, X pipe, stock mufflers.

Here is what happened ...

In September I took the car out to run an errand, once it was warmed up I ran it through the gears pretty hard through 1st, 2nd and 3rd, shifted when I saw the shift light which is set to come on at 5,800 rpm. Ran great, no problems. Stopped at the store and when I restarted the car it had a dead miss, I was only 4 blocks from home so I nursed it back. Pulled the rocker covers and discovered a loose rocker bolt on #4 intake. It was loose enough that I could turn the bolt by hand. Checked all the valve springs and rockers on all cylinders, pulled all the pushrods on #'s 2-4-6-8 after finding the loose rocker, none were bent or showed any unusual wear patterns or marks. Retorqued the rockers on all cylinders. ONLY #4 intake was loose. After that the car ran absolutely fine no noise, misses or anything unusual up until 2 weeks ago (approx 1,800 miles).

Two weeks ago I took it out for a trip downtown on a dry day and everything was fine, the car loved the cold air and ran great but I didn't get on it all. I think the highest RPM turned on the trip would have been maybe 3800 rpm give or take a few. The car sat for about 4 hours, the outside temp. was about 31 degrees. Upon startup I hear the noise in the attached video but very faintly. I nursed it home (approx 15 miles) and tried a little bit of that Seafoam stuff. The noise went away. I put another 25 miles on it and took it in for an oil and filter change (Royal Purple synth.). Put about 100 miles on it, ran fine, no noises.

A few days ago I start the car and get the noise in the Video ... same as before but louder now. Shut it off, pulled the right side rocker cover since this was where the problem took place the first time and once again checked all the rockers. None were loose. Checked all the push rods again, none bent. Checked valve springs, no visible damage. With the rocker covers off, bumping the engine over all rockers move equally. Oil pressure is 42-45 psi as it has always been since I bought it. No codes on the DIC, all plugs look the same. The noise almost sounds like its under the intake manifold but is slightly louder on the right side between cyls 4 and 6.

I would really appreciate any suggestions or opinions or predictions of what I will find when I start tearing this thing down to find the problem.


Thanks !

blazer427X3

Forgot to mention ... the car has about 15,000 miles on the engine mods. Total mileage is 59,XXX.

I cut open the oil filter, no shavings, flakes, chunks ... nothing bad.

gmmusclecarman

iTrader: (20)

you said it sounds like its coming more from the top end? im thinking it could be a collapsed lifter maybe?

blazer427X3

Yes, its up on the top of the engine. Almost like its under the intake but using the screwdriver method its like it comes from between cyls 4 and 6. With the valve cover off and bumping the engine over all the rockers move. The car doesn't smoke, it doesn't even run badly. After the incident in September with a borrowed tester according to my notes compression was : 1-180 2-185 3-180 4-185 5-190 6-185 7-180 8-175. I did not check vacuum or leakdown. Even though I found nothing inside the oil filter could it possibly be a cam bearing ?

DarkJuggalo

iTrader: (6)

sounds to me like a lifter.

blazer427X3

Thanks gmmusclecarman and darkjuggalo for the replies. A friend who listened to it in person thinks so too but the part that has him confused is the rockers all moving equally and the fact that all the plugs look alike. If it is a lifter do you think I wiped a lobe on the cam too ? Its coming apart next week and I will post pictures showing what I find if anyone would be interested. I am a little baffled by this one. Another person also said its possible to "spin" a lifter in the bore but I've never heard of this happening. His best guess is that maybe its the roller at the bottom of the lifter binding on the pin.

03EBZ06

almost sounds like a loose rocker arm. Take the valve covers off, pull the rockers off and inspect them all. Pull the pushrods and make sure they are straight. Push on the lifter and see if it feels compressed of caves easily.

blazer427X3

Thanks for the reply 03EBZ06, nice looking car you have. Impressive mod list and e.t. too !

I would love if that were the problem and although I checked the rockers and rods I think it would be a good idea to do it again before pulling the intake and heads.

Since I've had a rocker bolt come loose on #4 intake ... the incident that was my first problem I will do that again and re-check the rods too. I also like the suggestion about pushing the rod down onto the lifter to see if its soft, I didnt try that before.

Thanks again !

B

blazer427X3

gmmusclecarman, DarkJuggalo,

I wanted to post this to let you both know that you were correct in your diagnosis and to say thanks again for the replies from everyone. It was #5 intake lifter. It shows spalling on the edges of the roller right next to the bevel. I can also see the beginnings of spalling on #7 and #3. Odd that they seem to be failing on the drivers side of the car only. I'll be checking those lobes really close when I get back out to the garage.