Thinking about trading for another dsm advice?

[dsm4lif3]

I used to have a 1993 talon es wasnt the fastest car i drove but was deff a fun car to drive and i loved dsm's ever since and always been looking to get one. After my talon blew up on me due to timing belt jumping i sold it for a few hundred and picked up a 1991 civic which is my baby right now and i love it too great daily driver gets me everywhere with 20 dollars in gas haha.

But i found a 1999 eclipse oz that im looking at. He states that "the motor had developed a small knock or tick sort of thing after 2000 rpms at idle its fine still runs and drives good but has tick/knock." We are planning on meeting up this thursday when i have time i just need some advice. Im curious if its a knock or valve tap or what it is. Is there anything i should look in particular or listen for. I know i can tell if its knock if loss of power and what not. He said he had someone do a compression test and ran 200 across all 4 cylinders which i took with a grain of salt because i never trust anyone with this crap its all bs half the time.

 

[DSMTyson]

See if the tick/knock is continuous throughout the RPM range in neutral, or if it goes away at a certain RPM then comes back when the rpms come back down. Lifter tick is continuous, rod knock goes away at a certain RPM when revving and then comes back when the RPMs return to idle.

Usual culprits are lifter tick/collapsed lifter and rod knock.


I think...

 

[talonawd1991]

Are you trading your 91 civic for the 99 eclipse oz?

 

[dsm4lif3]

Yea now he tells me it comes after 2k rpm and goes away once let off the gas. So its deff a knock shit .. But yes 91 civic for 99 eclipse oz.

 

[talonawd1991]

Well if your willing to trade for a car you definately have to rebuild id say do it but as you stated your civics a great DD.

 

[dsm4lif3]

Yea well i posted this not knowing for sure if it was a valve tick or a knock until he just told me what i had stated above.

This might sound stupid but im still learning as im in college and dont really have much knoledge with knocks and crap. But knocks are due to play or not getting enough oil somewhere in the engine? Like as you said rod knock would that be anything in particular? if that makes anysense

 

[WES_393]

See if the tick/knock is continuous throughout the RPM range in neutral, or if it goes away at a certain RPM then comes back when the rpms come back down. Lifter tick is continuous, rod knock goes away at a certain RPM when revving and then comes back when the RPMs return to idle.

It's the other way around. Lifters tick until they are pumped with oil at higher RPM's. The larger 3g lifters in 4g63's don't tick because they fill with oil much easier at idle. A knocking rod will continue to knock throughout the RPM range since it's no longer floating on the bearing/oil film. No amount of oil pressure can stop that.

OP- In my opinion, rod knock is the worst thing that can happen to an engine. It destroys the crank, the rods, can break and be thrown from the block, contaminates the oil with metal shavings, etc. I would look up some videos of 420a lifter tick and 420a rod knock, then compare the sound to the car your looking at. The most common cause of knock is lack of oil pressure or clean oil to the bearings. If the knock sounds pretty bad and you don't want to rebuild the engine, I would stray from the deal.

 

[dsm4lif3]

Yea your right wes its probly not worth the trade because right now im i need of a dd for commuting to college and what not. Ill probly still take a look at the car and see whats actually up because maybe he just dont know what hes talking about at all..

But Wes just to clear up my confusion if someone were to say a engine had a rod knock to you. What exactly does that mean that is wrong besides everything that can happen. Is it caused by rod bearing i dont know if im making any sense at all but i just wanted to clear that up for me haha.

 

[bryanwheat]

If the engine has a rod knocking than it will soon blow up and need a new engnie, that is what it means. IF you don't have the money and mechanical know how to work on it turn the other direction and walk.

 

[WES_393]

Yeah, it's usually caused by rod bearing failure. The bearing lets the rod float on the crankshaft. Once that bearing has been severly damaged it will get hot and turn to dust. Without the bearing, the rod knocks up and down on the crankshaft which is what causes the sound. The failure is usually caused by a bad oil pump, too low on oil, water in the oil from a blown headgasket, dirty oil, bad oil filter, etc. So you can see how it would take an entire engine rebuild to not only fix rod knock, but make sure it doesn't happen again.

By all means I think you should still go take a look, it could be as simple as an exhaust leak that sounds like a knock. But if it sounds anything like this, walk away.

eclipse 420a rod knock - YouTube

 

[dsm4lif3]

Right ok thanks for your help man but yea im going back home thursday so im deff gonna still take a look after looking at that video i think i can deff tell the difference from something as serious as rod knock to a lifter tick and what not.