Hey guys.. this is how the story spells out. I have owned my 84 since about 80 thousand miles. Currently i have 155+k on it, and it is my daily driver. When i first bought the car i did a lot of drag racing.. I was at the strip atleast once, if not twice a weeks making my normal runs. From the first day i bought my car, i have always heard a faint knocking sound coming from what i use to think was the top end of the motor. I always thought it was a lifter or something, and never did much to correct it. My local mechanic said as long as it keeps running i would not worry about it. A couple of months ago i took it to a local engine rebuild place that provides warranty's on all their work. I was considering having a rebuild done, but money is certainly an issue for im full time in school, and barely can manage 30 hours of work a week. This covers my insurance, gas, ect.. Anyway, my whole point to this thread is, My car is knocking, two people now have told me they think it is the bottom end, (rod or main bearing maybe?) I need your guys opinion. I do not have a lot of money right now because i have to pay out couple grand in a month for next semester of school. Should i,

1. Ignore the knock like i have the past 2-3 years, and wait until i have more money for rebuild

2. Or, should i pull the oil pan and change the bearings and hope thats the problem.

I need to know if i opt for the second choice, would changing the bearings alone be dangerous, and do you guys think it would fix the problem.

I think i am capable of rebuilding the motor in my car. I helped rebuild motor in my old 89 toyota p/u, I have several friends who are engine savvy. What would you guys do with a budget of about $700? Any input would be great.. Keep in mind this is my daily driver.. I could take off work for a week if necessary (paid vacation time) :jester
Thanx and sorry for long jumbled thread..
Believe it or not, but im actually writing a report on flexible benefit plans in small companies. Im tired of being all gramatically correct and stuff :p:


[Modified by quiksilver458, 9:29 PM 11/6/2002]

 

Wrong section..

 

i know hehe.. asked two mods, but dont think anyone is on to fix :cry

 

Well it sounds like you definately have some sort of problem........ but fix it or wait?....... only the car knows for sure. I had a student a few years ago that owned a 5.0 Mustang that knocked............ we all thought it would blow at any minute ........he ran the guts out of the car for two solid years (and I mean he RAN it) it never got any better or worse......... last I heard the car is now owned by his brother who STILL runs the guts out of it and the sound hasn't changed any........ go figure......... I would have torn it down ........ he didn't and got away with it.............. :eek: :seeya

 

Sometimes (very seldom nowadays) a wrist pin can produce a very uncomfortable sounding knock. It's deep, rpm dependent, and not appreciated by anyone. You may be able to drive a car like that for 100k, depending on how aggressive you are with nitrous, etc.

For me, I would like to atleast find out which cylinder is the offending party. This can be a pain but you could use an automotive stethescope. Or, pull one plug wire at a time and note any change. When pulling the wire on the offending cylinder, you MAY note a significant change in tone. With no spark, the cylinder is along for a ride and no combustion stressing components. With that, any dropping the pan would allow a quick check of one or two journals. Of course, long as the pan is down, might as well do all.

Another diagnostic aid MAY be a cylinder leak down check. This MAY help determine if some ring lands have decided to collapse around the ring and give some "piston slap" which is also tough to nail down. Anything from the piston/rod area can give a characteristic deep knock. There are some enigne guys with really good ears. Not me. A knock's a knock. Hate em all.

SPECULATION HERE- With good oil pressure verified, supsect the bottom end could be ok. Bottom end knocks tend to get worse with corresponding drops in oil pressure. Though not always. General comments here.

Couple of quick questions. Is the knock consistent across temperature range, from start up(cold), to warm up, operating temperature, fairly consistent. Or, as the car warms up, the knock decreases slightly?

Does the knock vary a little bit when you use say straight 20 wt, 30 wt or 20-40 wt oil?

Anyway, also like to hear from others. Tough call.

dlmeyers 90 coupe zf6 3 speed shocks

 

Many great questions.. Thanx!!! I've put 70+k hard miles on the car. at startup the knock is non-existent, and slowly builds up within the first 2-3 mins of run time. I have noticed that when i apply the gas to say 2k rpms or more, the knock appears to disappear.. The engine will knock weather the car is cold, or hot, but really only at idle. If i apply the gas to about 12-13k i cant faintly hear it. Anything after that, its gone, or appears gone.

I was using a 10-40 oil for a while, an then my mechanic, (which i never visit anymore) told me to switch over to a heavier weight to help with the wear. Now im using the valvoline race oil.. a straight 50 weight. This is what he advised about a year ago.. The only thing i have noticed is that my car heats up to operating temp a lil faster. This im sure is because of how think the oil is. Thanks for the advise dlmeyers. I plan on doing firing up the car, and pulling spark plub wires to see if i hear a difference in the sound.. Also, If i, or you guys determine i should say drop the pan and just pull and replace the bearings, will that affect me in a bad way? I just assume let the car keep going since it seems to drive and perform just fine. I just dont want to run the risk of throwing a rod or something.. Thanx :jester


[Modified by quiksilver458, 12:14 PM 11/7/2002]

 

I had the same problem on my 85 w/ a knocking sound. it turn out to be my catalist convertor. Just a thought. :D

 

I honestly would not worry about it. enjoy your car. don't let shops tell you it could go at any minute, and you need to rebuild it....they just want your money....

 

Thats wut im thinking!! thanx guys!! :cheers:

 

I always had a faint knock (not a tick, but a knock like someone knocking on a door) at idle, one day traced it with a stethoscope to the fuel line in the engine compartment. Later found a TSB for "fuel line hammer" which specified isolating the fuel lines from the body to reduce the noise, but once I knew what it was it didn't bother me anymore. Just another possibility.

 

I worked on a 84 with a loud tap (sounded just like a lifter) Turned out to be a very loud injecter! Just unpluged one at a time wile running to isolate.

 

With that many miles I would just drive it.

I have a 92 LT1 with the same problem you just described so I am interested in hearing if you find out what it is. Mine drives me CRAZY! It has been ticking for 2 years ever since I bought it. I have taken it to two different mechanics and one tightened the lifters and the other replaced the rods. It still ticks.

It doesn't seem to affect the performance though but I'm afraid it will affect resale.

Good luck with it. :cheers:

 

I will certainly let ya know.. chances are i will hold off on rebuild until next year when i have more money and time.. :jester