valvetrain noise

[svandamme]

so i rebuilt my engine in februari, ran good ever since
last sunday had to do an emergency high speed dash for 240 km's... and it ran good, never ran to hot, mostly highway at 180km/h...

now this is the strange things

when i now do a cold-cold start , the engine fires up, and runs smooth , no excess noise

when i park it warm, then say half an hour later a do a warm cold-start , it fires up fine, and idles smooth

but when i give it the pedal , i hear a lot of racket from the valve train...sort of souds a bit Diesel engine like
oil pressure is good from the getgo, and it goes away after a minute maybe 2..

drove back yesterday , not so high speed
the engine seems to have all it's power, pressure and doesn't run hot... it also has the text book 944 fuel consumption.... 10 liter per 100 km...without trying to drive conservatively... so that seems fine... no smoke, no oil leaks... just that diesel like noise on a warm cold-start



has anyone every encounterd this?? any ideas what this could be??

i thought about the hydraulic lifters, but fail to graps how these would be more noise when slightly warm vs when completely cold.. it just doesn't make sense to me...

then i thought about the oil pressure relief spring doing something funky , and that a full cold block somehow resets it... but i have no clue as to how the oil flow works on the 944 . or how the mechanics of this problem would interlink....

[rudidelange]

Is it the valvetrain? Can you isolate the area where the noise comes from? Lift the hood, increase the revolutions and see if you can determine the area of the noise.
The lifter will only make a noise if they are not filled with oil. Maybe when it is hot, oil can drain from a lifter and then it takes 1 - 2 minutes to fill again.????

[svandamme]

it's definately the valve train or lifters... in that general area...

that draining... is that a common thing with hydraulic lifters?
and if so , is it a really bad thing? something that can cause catastrophic failure??

strange thing that it only happens with a warm cold-start .. it's not there when it's stonecold in the morning...

[rudidelange]

I had a lifter noise when my engine was cold, after 2 minutes the noise stopped. When I overhauled my engine I found that two lifters were bad, the oil drained from then overnight even if they were filled under pressure.
If the lifters loose oil overnight then they should be noisy in the morning when the engine is cold. I agree with you, lifters should not make a noise after a warm start up.
Is your oil pressure meter good?

[svandamme]

Originally posted by rudidelange

Is your oil pressure meter good?

moves up and down as it always has
high when cold
normal when warm

nothing special that would indicate it's not working as it should..

i did reuse the old lifters when i rebuilt it... i just took the engine apart for new piston rings, and rod bearings... top end looked ok and wasn't the reason for the rebuild ( blow by on the rings )

guess it's not to much hastle , i could get mysef 8 new lifters, take it out and redo that part...

what's the worst that could happen with this problem ?
assuming i ease up on the engine till it warms up and the racket goes away , i guess it's drivable that way right??

and if it would get worse, i assume i would be able to tell by the noise that would take longer to stop, and eventually it would keep making the noise... ?just don't have the time for it imidiately, and i do need wheels... need to go back 240 km's for the funeral...

[Razorback1980]

A collapsed lifter will not really hurt the engine to any great extent. It will cause that valve not to open fully and that will make that cylinder have less power than it will after it's pumped back up. I agree with you though that it only does it during a warm/cold situation...never heard of one doing that before. One thing I do when I have a dirty lifter is run a quart of automatic transmission fluid in the oil for a while. It's a great cleaner and maybe it will clean the lifter and stop the problem. I'm just not sure it's a lifter but I don't have a better suggestion either.

[svandamme]

thanks guys... just one more thing... in your opinion , the sound of a collapsing lifter.. would that sound sort of Diesel engine like?
just trying to make sure if that sound makese sense to diagnose it a lifter problem

[hpaulb]

Could. If you want to take a look, remove the lifters and test. You could check for a broken spring while there.

[svandamme]

Originally posted by hpaulb
Could. If you want to take a look, remove the lifters and test.

can't right now , funeral , need wheels

[Panzer909]

I had a clacking type noise related to what you are describing for the longest time and unsuccessfully tried the ATF flush several times. Tried the Seafoam trick and it worked. This may or may not work on a newly-rebuilt engine.

[svandamme]

metal clacking sound, yeah, that's about it..

seafoam ... that'll be impossible to find here in Europe.. i'll pull the camhousing and put in new lifters...sold the 911, got nothing else to wrench on anymore , so might as well give the 44 the attention now...

[Razorback1980]

Not sure what they sell in Europe which is why I mentioned the ATF. I figured they would have that for sure. I also like Marvel Mystery Oil if you can find that but SeaFoam is my favorite too. I posted a suggestion to someone in Canada not too long ago and they told me to think about what was available in their area so I was trying to do that. Every flat lifter I have had didn't really sound like a dieseling engine, it was more of just a loud tick. I think you have a different problem than the lifters, however I'm not sure what it is. Almost like an electrical issue causing the timing to be off for a while until a sensor indicates the proper temperature or something. Maybe the reference sensor reporting incorrectly or temperature sensor not reading the correct temperature. I'm just not sure though. Maybe even an intermittent DME problem. That is pretty common in these cars...have a spare one or know where you can borrow one?

Edited to remove Arkansas grammar!

[svandamme]

not the sound of a dieseling engine
but the sound of an actual diesel ( and not the modern ones those are to refined these days... )

i'll see if i can find some ATF oil... that's no problem...

[Razorback1980]

Sorry, I meant to say a diesel engine. It's possible to make it sound like that but it usually doesn't. I suppose if the lifter were completely flat, the cylinder would not fire at all and the engine would run on three cylinders which would make it shake quite a bit. But I can't imagine that would cause a lot of noise. And they would have to be pretty bad to do that. When it does it, pull plug wires to see which cylinder it is. I had a similar situation one time and it turned out to be the distributor cap had the spark jumping to the wrong terminal inside the cap for a short time. That leaves a small black line across the inside of the dist cap when it does that. What that does is it has the plugs firing at the wrong time and it's usually when the piston is trying to come up on the compression stroke. The ignition is premature and the explosion inside the cylinder is pushing the piston down while it is trying to come up...similar to a diesel. Just really hard to tell what it is from here but I still don't think it's the lifters. But then I've been wrong before. Let us know what you find.

[svandamme]

it's not shaking, and is running on all 4
there's not detonation going on that wouldn't sound like a diesel at all

[rudidelange]

Just a question
Where can you travel at 180kms in the Netherlands?

[svandamme]

Originally posted by rudidelange
Just a question
Where can you travel at 180kms in the Netherlands?

anywhere you damnwell pleased if there is an emergency

[hpaulb]

A metal sounding clank is usually that. Check your belt to see if it slipped a tooth. Pistons may be hitting the valves? If it's a lifter gone, no need to replace them all. There expensive. Take them out and test them. While there do a full inspection. Make sure it's not a bearing or ring gone and is just transferring the sound through the block to to top end. A bearing usually shows low oil pressure so it's probable not that. A bad ring will show on the cylinder wall. Broken valve spring - look for pieces-

[Eldorado]

i've got some pretty bad lifter noise going on in my car... thinking of using seafoam...
what line do you guys use?

and... what empty parking lot do you use so you dont draw attention by the neighbours/cover half your driveway in soot?

[JivenJim]

Simple thing to try. Add 1/2 qty oil above the Top mark indicator. You might be surprised how much this helps. Thicker oils seem to quite the engine a bit more.