1990civicsiguye

Most of you know i just did the zc swap.. well since i did it i have been getting a knock in the motor upon startup...once pressure builds up the knock will go away until i give the motor load around 4500 rpm... what is this issue is this a bent valve.. cyindler issues what. thanks for your help in advance..... Also one other thing the zc intake maniforld on the right side in the back as facing motor does not have the same wiring as the si did what is this extra peice that im missing on the zc some wiring thing... but no codes what so ever... later ill check to find out in a few...

1990civicsiguye

i know some one knows

JonGP4

a bent valve will cause a compression leak and ur car will eirther miss or run like ****.. ur problem is something bearing related, or you oil pump is going out thus not really working at start up. tear it down and check your clearances

blueHwrench

More than likely this is a lack of lube problem on start up. Meaning, no oil to lube something that moves at start up (usually it's top end parts, because the oil gets there last, before draining back to the pan). This can be caused by one or multiple things. Failing, or weak check valves in an oil filiter can contribute to this, or using a cheap filter with no check vavle at all. Using too high a viscosity oil, such as straight weights (30wt, or Valvoline 40 and 50 racing weights), or even 20-50wt. can cause this. A worn out eninge will do the same thing, because it takes longer for the oil pump to fill the wider clearences. A worn or failing oil pump (although I have PERSONALLY never seen one fail on a Honda in 15 years) could do this as well. One thing that may be ocurring that I have experienced alot of is cold piston knock. Hondas are notorious for it. For some reason, the factory usually sets those motors up on the "loose side". Meaning, clearences are usually on the high side of the spec. Subsequently, when a Honda engine begins to get some miles on it, and I've seen some new ones too, they develp a cold piston knock. It's been discussed several times in Service News articles, as well as been a rare thing people bitch about in the dealership. If it is a cold piston knock, it usually will occur on a cold start, and lessons fairly rapidly within a minute or two of running. Normally, you hear it worse when you free rev the motor on first start(which really isn't a good idea anyway), or if you take off real quick on a cold motor, and put some load on it, driving down your street. By the way, one way to help distinguish it it is oil related or not, is by watching the oil light as you start the vehicle. Pay atten tion to the light, while you crank, and start the engine. If the noise goes away EXACTLY when the light goes off, then most likely this is a lack of lubrication problem, not a cold piston or some other kind of problem.

MLogan

When I start my car, everything sounds normal. But when I go to drive it up the hill out of my drive way, it bogs down. This only happens when the engine is first started and goes away right after. Could this be the cold piston knock?

1990civicsiguye

ok guys and ladies.. thanks for all the help..
Now some answers to statments.. 1 i changed all the bearings in the bottom end.. rod and main so im sure that isnt it....2..... yea on startup that is when this happens so mabe that would do it i will take a compression test to try to make since of all this you know...3rd....I have not driven this at all since i swaped the motor i dont want to cause more damage than need be... But i do know that it also knocks at load... Also i have not taken the motor past 4500 rpm and i have only just put about ten miles on it since i swapped it.. let me know what you guys think .....thanks for all your help

1990civicsiguye

bump this up

blueHwrench

no, your problem is not related to cold piston knock. Basically, the only symptom is one that is heard, the knock noise from the engine until it warms up. What do you mean, "bogs down". Do you mean it has no power, until it warms up?