Y 1981 US shark. Just changed out t-belt and water pump about month ago.
Getting a knock on start-up, pretty loud. I'm going to see if the power steering bolts need tightening again, which was a problem before that produced much racket from the engine compartment earlier in the month but tightening it seemed to make it go away. Sound seems different this time, but unsure.
My suspicion is that it is a possible loose fan knocking on the water pump (what about that design in earlier sharks, anyway-- high speed fan attached to the water pump with three bolts and nowhere else). I will see if those bolts need more tightening. I am also concerned that the water pump is separating from the block and the sound is the impeller chipping away at the block (nightmare scenario) but that is just alarmism I think. I am getting no leakage, but I am getting steam from the tail pipe on start up. Someday I suspect I will have to get in there and do valve cover gaskets and head gaskets-- probably different problem altogether.
Do you have any suggestions? Because the sound seems to dissipate after warm up, although decreasingly so, I am wondering if it is a lubrication issue-- perhaps not enough oil getting circulated in the initial seconds of start up. Also maybe an accessory bearing going bad because of up-to-snuff or overly tightened belts? All "thumb pressure" tight. Any ideas?
Many thanks in advance.
81 5sp "moosgrunmetallic"
Well, I had a knock in my auto S4 about 9 months ago. I had let her sit a loooong time and on startup she knocked -- it was very hard to tell where
the know was coming from. Anyway, one day i decided to wash all the cat
pawprints and miscellaneous stuff off her, and so i pulled her round
front. she knocked like a mother ... but i decided to let her warm up, i
was tired of looking and not finding the knock. Couldn't tell if it was
top-end or bottom, but it sounded like oil-pan. AdamB thought it was a
head. My mechanic (a good one) thought it was a sticky lifter and said it
would go away.
The longer she idled and actually warmed (all gauges were good, oil press was pegged appropriately) the less she knocked. One good rev (I was expecting to pick little pieces of crank out of the sump) and ...... KABOOM!!!!!
No just kidding. No kaboom. Just a peaceful growl. I still don't know what
it was. Never knocked again. What does this all mean to you? I wish I knew
Heinrich ... Most likely a lifter which then pumped up and is fine , not unusual if the car is not driven for a while .
track car does the same thing after sitting all winter. scares you at first, but goes away in a few minutes and generally doesn't return unless it
sits for a while.
89 s4 shaaark
88 s4 track car
At 06:20 AM 2/27/2004, Theo Jenniskens wrote:
A few days ago I started my 1988 928s4 and it scared the sh&*tt out of me. The car made horrible noise, ran very rough as if a part of the engine was not running, and sounded almost like a rattling gun. I switched off the engine, checked a few obvious things under the hood, and then decided to start the engine again since all seemed in place.
The noise was still there, and the engine still ran very rough, but not as much as the first seconds. After a few moments the car started to idle normally again, but I seem to hear the lifters make more noise than usual. I drove the car gently for about 120 kilometers without any obvious problems. (The car was not in storage but is driven every other day, and temperatures are about 0C (32F).)
So what happened? Did a valve get valve stuck? Lifter (Hydro) stuck?
Any permanent damage to be expected?
While there are quite a few possible causes for loud clattering noises upon cranking, few of them will go away...
One of the few that can appear and disappear is due to sticking or collapsed hydraulic valve lifters. If one or more lifters collapse, there will be excessive clearance in the valve train, causing a loud clacking sound.
One possible cause for collapsed lifters is a leaking oil return valve.
There is a one-way check valve in the cylinder head that should retain the oil that is in the passages in the cylinder head after the engine is shut down. If this valve leaks, the oil is not retained, and runs back into the oil pan.
When the engine is cranked the next time, the oil pump must fill the empty passages before any oil pressure can get to the lifters to fill them, and the lifters will clack until they are filled with oil under pressure. When the engine is very cold, it takes longer for the oil to circulate, giving more time for the lifters to collapse, causing more noise.
If this is a one-time occurrence, I wouldn't worry too much. If it happens repeatedly, some possible solutions include:
- A thinner oil for colder temps.
- Cleaning the oil return valve. This isn't a trivial task, requiring the removal of the cam cover.
- A better grade of oil (not usually the problem on a 928!).
- Changing the oil more often (almost never the problem on a 928!).
ATF's are often cited as "fixers" for a number of automotive issues Sometimes they are correctly applied (certain manual gearboxes etc) and sometimes not (as an upper cylinder lubricant and etc)
ATFs typically have a very LOW rate of detergency as there are no combustion related deposits like varnish and carbon, soot etc in the Autotrans.
Unless the design is faulty (a number in various engine families are) or the oil is less than suitable (too thick/thin, foaming etc) or it has a worn broken or incorrectly adjusted component - you can usually blame a build up of deposits or a transient contaminant. Varnish is a "progressive" deposit primarily caused through oxidation and less likely if the engine has been on a good quality A3/B3 synthetic oil
ATF MAY temporarily "fix" a number of these things, it is thinner than most engine oils, it is free flowing and non foaming, it may flush out a contaminant.
Many years ago we used to run a "cleaning dose" of kero and a new filter with the engine hot and lightly loaded. The "cleaning cycle" process may take a few hours and a light road run will usually help too.
The best idea is probably to try a mixed fleet "CI-4/SL" HDEO (Castrol RX Super 15w-40 is great) oil and 10% kero dose as mentioned above. Then use a 15w-40 CI-4/SL HDEO as the engine's oil for about 1-2k.
These high detergent oils are excellent at removing deposits from ring land areas etc too. They have very good anti-foaming additives
If the noise was deposit/contaminant related it should be gone or now last only during the first 20 seconds or so after startup which is "normal"
Early 928 engines may benefit from the installation of a pressure relief valve with a sealing ring. This prevents air uptake via the vent bore
Some engine cleaners may work - I would never use any. The major diesel engine makers always resort to short term oil/filter changes with kero dosing as a last resort. Diesel engine deposits caused through incorrect oil use would curl your hair! I have seen it up to 3cm thick - like in many Euro petrol engines during the 50s-60s
Doug et al,
I added two quarts of Risoline to the Mobil 1 oil (less than 2000 miles on the oil) and the noisy lifter went away after a short warm-up run.....and even after cooling, has nor returned. I will put another few miles or so on this crankcase concoction and then do a complete drain and replace with Redline Oil. If the lifter noise returns with the Redline oil...I'll add a quart of Risoline and continue. I think it must have been a bit dirty in there, pre Risoline, or the recently added Mobil 1 contributed to the noise.
I don't really remember it being that loud when I was using regular dino oil. Maybe the thinner oil makes it harder to pump up a lazy or dirty hydraulic lifter? I know some people don't like Mobil 1...they may have a point.
Thanks for your advice, if the above treatment doesn't fix it, I now have another bullet in my gun.
About a month ago I did an oil change and put in Mobil 1 0W-40, plus a bottle
of Wynns Hydraulic Valve Lifter Treatment, as my lifters were clicking.
Immediately noticeable was the absence of any more lifter clicking, and the car running much smoother, but more interesting was that now when I floor the accelerator through the rev range I no longer see any smoke in the rear mirror. Used to give out a few puffs of grey smoke on hard acceleration and high revs.....now nothing....goes like a scalded cat though!
1984 S2 with GT 5-speed box