So i have a hand built SVT Cobra...its supposed to be a race car right??? i guess not. my friend and i had a race from a dig and i ran the rpm band thru 1,2,3 and part of 4. i lost cuz he has AWD. anyway, driving home i have a nasty knock in my engine. it knocks accordingly with the rpm's increasing. Is it a lifter or anything....someone please help..

 

If you spun a bearing in a mod motor that would be one of the first I have ever heard of. But if it changes with rpm its either valve train or bearings pretty much every time.

 

so your puttin your money on valvetrain....i know cams are expensive but price range to fix do you think more than 1k???

 

If the knock doesn't go away after awhile of driving its probably going to be valvetrain and not your lifters. My gf has the same thing on her eclipse. You can hear it moderately well at idle, but when you accelerate it gets quite loud.

 

I can't say because I'm not there and its hard to tell over the internet you know. If it was me I would start by checking out the valve train. Check the oil level and make sure there is enough, pull the valve covers and see whats up. After then its time to pull the pan and pull the connecting rod caps off.

 

i know nothing about internal engine, and i dont wanna **** something up, take off what pan???

 

oil pan

 

you beat the bearings out of it. Time for a rebuild.

 

i changed the oil in it and made no difference, still the knock is there...you still stand by the bearings?

 

bearings.


Heres the steps you need to take judging by your posts:

1) Take car to performance shop
2) Say Fix this.
3) Pay Mechanic.
4) Be happy.

 

From what you are saying ,it does sound like a bearing. If the noise is a very low pitched "thunk" that sounds like its coming from the lower part of the motor, then its a bearing. If you continue to drive the car you will do damage to the crank. When you changed the oil did you see any metalic glitter in the drain pan?

If you dont know much about engines I would not try to fix this myself. Follow Steeda's advice.

PS Dont let your sister fix it either. Check around and get prices from good shops and good shops only!

 

Chaning the oil will do nothing!!!! to fix this car.

BUT, if you did not toss the oil, run a magnet through it to see if there are any small peices of metal in it. If you are lucky, the problem is in the head. If you are not lucky, you could be looking at a complete re-build.

This si what I would do before spending any money on a mechanic.

1 - You were right to change the oil, but you need to inspect it.

2 - Pull the plugs. Look for damage on one or more of the plugs such as something hitting it.

3 - Then, check compression in each cylinder. If you have bad valve, you will not have ANY compression in the cylinder.

 

BTW, if it is a bearing, the motor is toast anyway. I am not sure if I would be worried about makig it worse.

I have been through two motors.....I know the sinking feeling.

 

the bearings are on the crank right??? and i ran a magnet through the old oil and it didnt pick anything up so next step is pull the plugs, but i have no idea how to check compression. also its not a thunk, its more like a tap, or a real light knocking. i also dont see any difference in performance, i dont take it over 2 grand but still, no bucking or anything of that sort.

 

You need to listen and figure out if its coming from the top of the motor or the bottom. And the bearings that fail and or spin are either crank or connecting rod bearings. But would change with rpm, but so would a valve train problem. Since you are unsure of what is wrong you just need to have it towed to a shop and checked out.

But I honestly never heard of that happening to a mod motor. However my friends 99 had a similar noise and he thought he spin a bearing. Turns out the C.O.P. on two cylinders had broken off, and the plugs backed out and it made a weird ticking sound that changed with rpm's. I thought for sure it spun the bearings till I heard it and I could tell it was from the top of the motor.

You really need to figure out where its coming from.

 

Spike is right.

If you spun a bearing, you would know it by looking at the oil. It would be very metallic in appearance.

Internet diagnosis is really hard.

If the car were mine, I would pull plugs, inspect and check compression. Doing a complression check is really easy. Rather then explain it, see if you have a family member of bud that can do it with/for you. You could check the entire motor in about 45 minutes. You just need a guage which can be gotten for $35 bucks or borrowed from an auto parts store.

When the piston moves it, it makes compression. That is how the car makes power. On a new motor I think the compression should be somthing like 180 psi (though, I forget the specs). If a cylinder is bad, the compression will be low. For example, somethign like 100 psi would indicate a bad cyclinder....perhaps a bad ring.

If you get 30 psi or less.....even zero, then it means you either burned a hole in a cylinder or have a bent valve.....the piston is not capable of holding pressure. Then, I would get a scope and look inside the bad cyclinder.

With a bad cylinder, you should notice a loss of power.

The reason I would do this is that it is easy enough to do yourself and it would sort of paint the picture as to the extent of the problem. If the compression is good all around, it is likely that the problem may not be severe.

When I blew my last motor, doing a compression check found two bad cylinders. One had a cracked ring land, and the other....well, we actually found a loose screw that was banging around and got caught in a valve. It completed dicked-up the head.

A dicked-up head could have been easily swapped-out for a new one.....a broken piston meant the motor was toast.

If this is beyon your ability to do yourself, I would avoid driving the car and get it to a shop. You might be looking at something that can be fixed vs ruining the motor completely.

If nothing else, pulls the COPS and make sure the plugs are secure.

 

Also, check the oil level! Again, easy to do. If it is low, then we need to figure out where it went.

 

took it to a guy that used to work for ford, modulars hes had lots of experience with, he listened to it and narrowed it to top end, then confirmed my and my dads beleifs by saying hes almost positive its a stuck lifter

 

Like I said friend has the same car with similar mods even. I would pull every COP and check every plug to make sure they are tight. He had to replace two COP and of course replaced every plug while he was at it.

 

Could it be the timing chain guides???