long story short...

Bent the rods a long time ago...got new rods (stock)...put it back together...

runs awesome for a week...

cruising down the highway and it just runs like its running on 3 cylinders AND (heres the bad part) there is a loud knock...so i limp onto the shoulder...weird thing is the car isnt or wasnt smoking. just running very very rough with this loud knock every 1.5 to 2 seconds. whatever is hitting its hitting very hard because when it hits it will make the engine rpm drop a couple hundred...

car is towed home.... i take the plenum off...number 2.4.6 cylinders are black with oil... (oil ring maybe???) but here again is another weird thing... the num 4 cylinder blows air up the intake runner????

So maybe a valve is bent??? and maybe that is what is hitting....

Cant tell you how frustrated i am with all this

 

I am sorry to hear that. The best thing for you to do now is to get her under the knife and fix her up from a good mechanic. Do it quickly so you can set this all behind you.

 

sorry to hear - sounds bad.

you built the motor and only changed the rods? who built it and what were the actual specs? sounds like someone didn't do a good job...

 

There is always a risk when you repair an engine that had a failed rod.

I spent a lot of money and time on a motor that threw a rod (not a 350Z) only to discover that the engine block was cracked.

Get a new motor !

 

what are you runnin on your motor?

 

I built it myself and not just the rods...everything was replaced with new stuff. instead of nissan bearings i went with cosworth. the heads were untouched. all new gaskets...spec'd to stock specs according to service manual. motor ran great and smooth. im no engine builder but i feel i did a pretty good job with everything. guess i wont know what happened forsure until i take it apart again...

 

it has the greddy tt kit with supporting mods...

 

why did you get stock rods after you bent them the first time?

 

had eagles and wiseco pistons at one point...but sold them after fiance got pregnant...soon as this is over im selling the whole thing...

pretty certain its not a rod issue this time

 

oh and the reason they bent was because i just made too much power so the plan was to not go for that much again... and to save a little money but thats a joke with FI right haha

 

I know how you feel my engine hydrolocked this week after I got a turbo put in... The worst part is that I didnt even get to drive it!!

 

bullet proof it. you are learning a valuable lesson today....do it right the first time. I broke a ring land spraying 150 shot of nitrous and am now doing a fully built long block with sleeves n all. Now my motor will hold all the boost you can throw at it plus the nitrous. It may take alot of money to get there....but its less money than doing it twice.

 

it just seems to me that its not the bottom end at all....

my reasons are:

one: the knock is not a constant knock. if it was a rod/bearing/piston ring of that nature it would be a consistant knock and would increase with revs...

this is what it sounded like when i bent the rods it was a quick ticking or slapping sound as the bottom of the piston skirt was hitting the oiler bar.

two: this new knock is just that...a huge knock...almost like the top of the piston is hitting something ...head/valve... hard enough to cause the rpm drop.

three: why the hell is air coming out of the #4 intake runner??? that is not right. air should be coming out of the exhaust side naturally so something is amiss there...

tonight i will do a compresson check to see what is going on there and the other cylinders.

i would love to go all out with a sleeved block and all forged internals but the money just isnt there at the moment.

 

Thats the moral of the story. If you have the change to TT, you should have the change build it right. If you dont, dont waste your time and money.

 

thanx for the encouragement

 

sorry to hear about all this. let me know if we can help you out with anything.




this is the reason we have 1500 dollars in nissan bearings sitting here, all 15 different sizes for the mains and all three for the rods. it takes a lot of time to fully blueprint an engine and make sure one hundred percent of things are perfect.

good luck with everything!!

 

ok so first off i didnt "just slap some rods in there and call it a day" cut me some damn slack here and not assume that i know nothing just because i post a question on here. There are plenty of ppl on this forum and not that are running stock blocks. also the term "blew" in this case is kinda harsh because nothing blew the first time. The rods bent. whether thats blew or not is all opinion to me. blew to me is one stuck out the side of the block. Its so easy to tell someone well you should have built it in the first place...it almost like well damn russ why didnt ya think of doing that in the first place haha...well like all who are running stock blocks they thought of it but then saw the added extra cost and decided against it. and thats fine until something goes wrong or you push it to hard in my case. then everyone flames the **** out of you for not building it...why? if it was my perfect world believe me i would have. but sadly that option was just out of reach for me at the time. As for the future of the car...i have no clue. and you are right in saying if i did sell it i would sell TT stuff and buy a new motor. thats only the right thing to do. i know myself i wouldnt want to buy a motor that has been apart twice...

but thanks for the luck because i sure could use some. and yea it is pretty tough to stop...

 

got the valve cover off...turn the crank and the exhaust cam does not move...

is it possible to switch the cam gears in the vq????

thinking i may have

 

I do not know if it is possible to mix-up the cam gears, sorry.

But I have broken camshafts before.

Sounds like you have a catastrophic problem. Keep us posted.

 

Missed a few teeth when putting the timing chain on maybe?

No clue, I know my friend had his mustang do that on him and it sounds almost exactly as you described. He ended up bending an intake valve. His is an interference motor, however, so not sure how much that helps.

The part where you mentioned that it happens every second or two seems like it would be on the valve side since the cams do 1 rotation for every 2 turns of the crank...