Will pre-oiler help start up knock?

Hi,

I had my 350-4 (hi-comp) rebuilt last year. The engine has around 3000 miles on it. It has developed a slight low end knock on start up (I stopped driving it after the knock started). If I turn the engine over for 4 to 8 seconds before starting the knock does not happen (I have driven it a little this spring). I had the car looked at by a local shop I use. They checked for loose flexplate bolts and check for flexplate cracks (none they could see). They think it is a main knock.

Here are some oil pressure readings and such.

Using Rotella T 15w-40 (thinking about trying the Rotella 5w-40 synthetic). (I had the knock with 10w-30 conventional also,I also used a single 30 wieght oil and got the same knock).

Using a Wix filter.

Oil pressure (I do not have a tach)
Startup (cold) =50
Normal driving (warmed up, 50 m/h aprox) ==30-40
Idle (warmed up) =10-15 closer to 10 while in drive.

Stock oil pump (also thinking about putting on a TA booster plate)

Other than the start up knock the car is driving great at this time (but I have not driven the car allot since the knock started).


The engine is under warranty until Mid June 2006. The rub is the work was done in San Diego while I am in Idaho (long story). Per the warranty the San Diego shop has to do the warranty work. After reading the great information in this forum I have some doubts about the San Diego shop. With the price of gas and my doubts about the San Diego shop I am wondering if it is worth talking the car back to San Diego. I could probably put in a pre-oiler and a TA booster plate for the cost of talking it to San Diego and getting it back to Idaho.

The engine is stock. I do not plan any high performance modifications to the engine. I would appreciate your input on my problem.

Thanks,

 

Hi Tony,

The good news is I'm not disturbed with your oil pressure readings, though 15w-40 seems a bit thick to me. Yes, a pre-oiler will always help, it should give you the same quiet start you get from your 4-8 second cranking. The booster plate is a good thing all around, in my opinion.

I'd be interested in seeing your oil pressure readings above 4000 rpm to see if you're still getting the 10-14psi/1000 rpm I think you are. Those higher engine speeds under WOT are where you really need to know where you are. Your comments about the performance level of the engine and what you want from it make me feel better, too.

The bad news is I don't know how big those bearing clearances need to get before the problem becomes audible; even the race engines I've built in the past with over .0025" bearing clearances have been quiet. I'm guessing you may well have more than that down there somewhere.

The warranty issue is a bummer, but like you said...I'm not sure you'd want them to work on the engine again anyway!

My $0.02,

Devon

 

Mine too....

My GS350 has the EXACT same noise you describe. After 8-10 seconds it's gone. It won't return unless I let it sit for a couple of days. I also am running 15W-40 Diesel oil. I do that for the additives that have diminished in standard gasoline oils and the SUPER HOT weather here in South Texas.

I kind of look at it this way: Under normal operating conditions the engine is basically silent. I have the exact oil pressure readings you do as well. The engine runs strong. I take it really easy when I crank it up....and let it warm up good before I get to letting the horses fly ! When it starts to loose oil pressure OR the noise becomes apparent during regular operation or takes longer to go away, then I'll worry. Until then, I'm going to enjoy driving it.

The only factor here is that you have a warranty to take advantage of. I built my own, and unless I really screwed up, I know what my bearing clearances are....and they all checked good.

Might help if anyone else can chime in here and tell us if they have similar noises as well? o No:

 

Are you sure its not your valve lifters? They can sometimes drain down if the engine hasn't been run for a liitle while. Its been my experience that if main or rod bearings are knocking they usually get worse as the engine warms up and the oil gets thinner, also the hot idle oil pressure would probably go down to almost zero. Just a thought.

Marc

 

I absolutely agree, it sounds more like the common symptoms of the lifters bleeding down.
Regardless, I'd be hesitant to drive the car if you really do have a rod knock.
Find out for certain where the noise is occuring.

 

i had a slight knock after i drove my car for an hour or so. i replaced the mains and rod bearings when the old 1's were good and i still had it. After i put on headers the noise went away lol. I still have no clue to what it was. Have you checked the rocker arm Shafts? on cold start up's i'll have a little ticking for a few seconds and then it goes away. Maybe your shafts are worn and your just hearing that. I used a long screw driver and put my ear on the handle end and went around checking for that knock and i never found it any where. Right now i use valvoline 20-50 and my oil pressure is 15psi in gear and warmed up and 20 in park. try draining a quart of oil and replacing that quart with some diesel fuel and let the oil system flush for 20-30 minutes and change the oil. I'd really just pull the driver side valve cover and check your rocker arm shafts. It wont take but 30-45 minutes to take it all apart and then put everything back together.

 

Yes, I'm using a PF24 AC Filter. In my case, I have always suspected lifter leak-down. I don't KNOW that for sure, but as you guys have stated, that makes sense. Lifter pump-up time doesn't bother me in the least. I suspect what we are both hearing is valve-train related seeing it is not a "deep" knock and oil pressure is "normal".

70LeSabre350: The suggestion here to check your rocker arms and shafts is a good one. I'm pretty sure mine is lack of oil in the lifters after sitting.

Buicks oil kind of funny on the valve train compared to some other products. The oil has to come up, pass over the first cam bearing before moving on to the top end on the drivers side.

Thanks for chiming in guys....I'm anxious to hear more ! :TU:

 

Hi Tony,

Take a long screwdriver and place it on each valve cover. Put your ear to the handle and you will hear valvetrain noise. Lifters that are not pumping-up are creating excessive lash between the rocker arm and the valve stem. You will hear it plain as day.

If you are interested in a good, reliable per-oiler.......you can view this thread.

http://www.v8buick.com/showthread.php?t=103346

PM me if you might be interested.:TU:

 

My lifters rattle on startup if it sits more than a couple of hours. Bought the cam and lifters from poston. They started doing this almost immediately after I installed them. I hate the noise so much that if I need to move the car in or out of the garage I push it. I only start it when I'm going somewhere. The oil doesn't matter. The lifters just bleed down. Makes it sound like a real POS.

 

I had one of those exact knocks in my 350, when I changed my cam I saw that a rocker arm retainer (little plastic push on pin) had fallen off and caused the rocker arm to wiggle around everwhere, I put a new retainer on and no more noise. I really was not expecting it to fix it, especially with a motor that has more than 90,XXX miles. It made me happy.

Erik

 

Thanks for the input.

Here is bit more info. The noise happens at start up. It seems to come from the drivers side of the engine. After the first start the noise does not happen on subsequent starts. If the car sets for a few hours and the oil drains back in the pan the noise happens again. I have not heard the noise while driving. When the engine is warm the oil pressure has been good. Warm idle pressure is good also. When I had to oil light hooked up I never had the oil light come on while driving.

Oil pressure (I do not have a tach)
Startup (cold) =50
Normal driving (warmed up, 50 m/h aprox) =30-40
Idle (warmed up) =10-15 closer to 10 while in drive with breaks on.

I say noise because I am now unsure if it is a main knock or lifter noise. I will try to record the sound this weekend and post an mp3 of it.

I will check out the lifters. Are the valve lifters bleeding down a major problem? How can this be fixed? When I pull the valve cover what should I be looking for? I will try to locate the noise first before I take anything apart. Do the passenger side lifters get oil before the driver side lifters?

Larry I am use a Wix filter. It does have an anti-drain back valve. Do you think the AC Delco PF-24 Oil Filter is better than the Wix filter? I may try one and see if it works better.

Thanks for the info. I will try to post this weekend with more details.

 

Tony,

In the oil filter the anti drain-back valve is what is important. Both the AC and the WIX filters have these. I tend to be of the opinion that WIX filters are of EXCELLENT quality. A filter with a silicone anti drain-back valve tends to perform the best over time.

If you believe it is a valve train noise, then coming from the drivers side would make the most sense knowing how the oil is supplied to the top end.

See if you can isolate which side the noise is coming from. Park the car where you want to work on it. Let it sit a couple of days, (as to replicate when it is the noisiest). Remove the valve cover you suspect the noise is coming from. If it were me, I would rotate the crankshaft and go from cylinder to cylinder at TDC and check the rocker arms. The noisy ones at this point should be loose....such as you can rock it back and forth. Lifters that are still "pumped up" will not have as much free movement.

 

what exactly does it sound like?

Chances are it is lifter noise. You turn the engine on it rattles like a can of marbles for about 5 seconds then quiets down. If so that is lifter noise and all 4 Buick blocks I have owned have done that. Including 2 within a few months after a rebuild. I've been told it is due to collapsed lifters, although I personally think it is because the stock buick oil pump just takes a few seconds to get oil up there. I bought the high-volume/high pressure oil pump modification (the one where you actually use bigger gears and drill holes and add a spacer to your timing cover to increase the volume of the pump cavity). This fixed it.

DO NOT buy just the high pressure oil pump spacer plate . That will make the situation worse. The buick has a positive displacement oil pump and you need the longer gears (and a longer pump cavity) to actually move more oil up there, not just higher pressure oil.

I would also reccomend a lower weight oil versus a higher weight one. The thicker the oil the harder it is to pump around cold.

In the unlikely event you have a rod knock then the engine needs to be replaced while it is still under warranty. A rod knock will generally be deeper than valve train noise and there won't be as much of it. More like thump-thump-thump-thump.

 

It is not a major problem at all. Its just annoying and embarassing. If its the lifters you will have to replace them. Some people have taken them apart and cleaned them. IMHO that's just too much work and you could end up with the same problem when you're done. To gain access to the lifters you need to remove the valve covers, rocker shafts, pushrods and the intake manifold.

 

sdmahr,
Thanks for the description for checking the lifters. I may try it this weekend.

Auburn2,
Thanks for the description of valve noise vs low-end knock. I still plan to get a recording of the start up and post it. I would like to get some opinions on the noise.
About the TA booster plate and hi volume oil pump. I have seen other posts saying the hi volume oil pump will cause early failure of the front cam bearing. I know TA Performance does not recommend hi volume oil pumps for stock engines. TA has recommended the booster plate with the adjustable pressure regulator. Why to you feel differently about it?
I was thinking about trying the 5w-40 Rotella T synthetic. I like the additional additives the diesel oil has over the current gas engine oils.

70aqua_custom;
Thanks for the analysis of lifter bleeding down (I hope it is the lifters).

Would a pre-oiler help reduce valve train noise? If it does I may put one on. I will get a recording of the start up and post it this weekend. Thanks for the great responses.

Thanks,

 

I wouldn't worry about the cam bearing

I don't see how it can put more stress on it then the valve springs and fuel pump do. In any case building a performance engine would not aleviate that. I've never heard of "high performance cam bearings", and the other stuff associated with a high performance build like stiff springs and large cam lobes (in addition to the hi volume pump) would put even more strain on the cam bearings.

I will note however that about 20K miles after I put on the high volume oil pump I did shear the distributer gear pin. It might have failed anyway seeing as it was 40 years old, but I am sure the extra stress from driving the oil pump didn't help.

If you are really worried keep a light spring in there to keep the pressure near stock. Then you will still have the extra volume and that is really what is matters most.

As I said I would not use the high pressure spring and plate alone. If you are worried about the high volume pump I would just stick with the stock setup. Getting a new stock timing cover will probably improve oil pump performance quite a bit since almost all the used ones are scored pretty bad.

If you replace your lifters you should replace the cam as well as the lifters and the cam lobes wear together during break in. A new set of lifters can flatten a camshaft. I can speak from experience here. I replaced the lifters on my old 350 for the same reason, they destroyed the cam so I needed to replace it (with another new set of lifters). And the worst part is the new lifters didn't even fix the problem.

 

I had the very same rod knock on a cold start if I let it more than a day. I added the pre-oiler and knock is gone. And it was rod knock, I've been around car long enough to know the difference. The top end is great and it burns NO oil, so I considered it a good investment to get more miles before I spin a bearing, which will be the next problem I'm sure.

I'm looking at a 71 long block delivered for under 2K, I'd need an intake, pan, valve covers ect, but I have that covered.

Whats a new timing cover going for these days?