[94Stepside]

Hey everyone, I was wondering if anyone could help me figure out a problem im having with my truck. When its cold and i mean very cold, the engine fires up fine but everyonce in awhile it struggles, makes some clunking noises, and then goes back to running fine, once the truck warms up it doesnt do this. It usually only does it when sits overnight at very cold temperatures. Im not wondering if maybe i have a clogged oil galley and the moving parts are sometimes not getting the oil they need, or maybe the oil is too thick? Or could it be a problem with the fuel injection system? Im really not all to sure, so any help would be greatly apprciated. Thank you

 

[_nar_]

Umm clunking noises? Could you get a sound clip or describe them better? Sounds kinda strange. How many miles? Ever sea foamed it?

 

[94Stepside]

dont know if i could get a sound clip, but basically it sounds like a hallow metal knocking, i dont know if that describes it any better, it has a little over 200 thou on it, and no i've never sea foamed it.

 

[red suburban]

what weight oil are you using? whats the outside temp? your fuel system is a tbi, easiest way to see if its temporarily not sending fuel is to remove the air cleaner, fire up the truck, and look down the throttle body. if the truck makes its noise and the amount of fuel flowing is reduced temporarily, then its a fuel problem (filter most likely). if the engine has the problem and the tbi doesnt do anything, then its not fuel related.

personally, i'd pour a bottle of either b12 or seafoam into the engine oil, as well as unplug a vacuum connection, and run about 1/2 of another bottle through the vacuum line (you dont poor the fluid into the vacuum line, stick the line into the can and let the engines vacuum suck it in), then engine will need to be revved when doing this, because either b12 or seafoam running through the vacuum will bog it down while it cleans out the motor. if your motor is even remotely dirty (as they usually are) your truck is gonna smoke up a storm, bigtime.

 

[red suburban]

200k miles and never had either seafoam or b12 run through it? it definetly needs it. after you do this treatment (with either b12 or seafoam run through both the vacuum line and poored into your crankcase) make sure to change your oil/filter. try using 5w30, see if that eliminates the problem.

 

[mvnvltn]

I may be time to replace the lifters. They are probably getting tired.

 

[woodchuck2]

Did you check for codes, this model year didnt offer much for codes but i would suspect a bad knock sensor to begin with. Have you checked the play in the distributor drive.

 

[malibu795]

you lifters are get stuck compressed. whihc will leave exsesive play in the valve train it will sound like a hollow knock. rod are a solid knock.
take it easy till it goes away. for me it only lasst about 30-60 seconds oilpressure was round 60-70psi when my sbc did stuf like that

what oil are you running right now???

try get some 10-xx or 5-xx in there for those cold starts. i would be looking at a top end rebuild. including cam.....

you have a hydrualic roller cam the cam itself run 250 the roller run about 150-200. it can be done with the engine in the truck.

 

[malibu795]

second thought you could get a sbc from 87 to 99 and build it till the engine in the truck goes then swap. the 305s were in everything along with the 350s if you get a junkyard 350 grab the ecm as well. for 600 bone you can rebuild a sbc with the hyd roller cams


just stateing options

 

[mr_udy]

Not sure if this is the same, but my wifes old sunfires oil pressure bypass would stick when cold. When very cold, engine would see extreme oil pressures as a result of it and run the lifters solid. Thing would hardly run with tons of valve overlap or lack of compression. I dont remember any knocking but If its the same sorta thing...cold only, maybe what I did will work for you...cheap and easy.

Since the sunfire fix was an oil pump replacement (required lots of teardown), I opted to try a synthetic equivelant oil because even with same viscosity (a measure of oils ability to "shear"), synthetics have a lower cold pour point (will flow readily at lower temperatures than conventional oi-different from viscosity). I figured its worth a try. It worked, no more cold weather issues. When I sold the car, I told next owner..."always use synthetic oil!".

FYI: I dont use synthetic in anything else....just for cost reasons...

If you try it, and it works, please respond...interested if my fix will help you.

I know of many TBI 305/350s running well past 200K w/o rebuild....

 

[Duromax04]

Time for a 350, or better yet, 383 stroker. That will fix it.

 

[red suburban]

200k is a fair amount for a small block chevy, but it can go farther. i had an 89 1/2 ton suburban with a 350 that had 330k miles when i sold it, no engine rebuild, 2nd tranny, rear axle had been replaced with a 14 bolt, ran great.

 

[94Stepside]

Well, im defineatly going to add some sea foam to her, but not till my next paycheck, i also plan on changing the fuel filter, and trans filter, also since she has hit 200k i figure it cant hurt to give the whole thing a good look over. Thanks for the help and suggestions, this place is great, it was barely a day and i already had 10 or so response, thanks again.