noises and things

[1990LTD]

My car knocks slightly on a cold start but goes away. I don't know when it goes away seein' as how I'm driving at the time.


I've read that it is a common thing but I don't know why it happens - What is the knocking sound? It makes it sound almost diesel-ish. the common quasi-fix seems to be lucas and more driving.




another noise: my alt belt needs replacing as it squeaks now, new one is on the way. but i don't know if i can hear the fan itself being noisy. what parts of the fan can get loud? any bearings or anything in there that need attention or anything along those lines?

[87CrownVic]

If you are hearing a diesel-esk noise, it would most likely be a rod knock or excessive piston slap. Upper engine noise is usually rapid and much higher pitched. Check your oil pressure with a manual gauge if possible. There is the slim chance your oil pump is suffering from excessive wear and/or a cracked housing. This would obviously be a more affordable and easy fix, just replacing oil pump and pickup. However, if it goes away once the vehicle is at operating temperature, you might want to consider SAE30 and the Lucas along with allowing your vehicle to reach operating temperature before you start driving.

As far as fan noise, you shouldn't be hearing any sort of squeaking or squeeling coming from the fan itself. You may want to make sure the fan drive pulley is clean and free of grease/oil before installing the new belt. Visually inspect the fan blades for cracking/excessive wear and make sure none of them are loose at their mounting rivets to the hub. A loud droning noise can be heard from your fan if the thermostatic fan clutch has failed, causing the fan to spin at engine RPM at all times. You may also hear this noise when your vehicle is cold and you first start out on acceleration(normal). The fan is also bolted to the front flange of the vehicle's water pump. If the water pump shaft bearing(s) have failed, the fan will sometimes make contact with the fan shroud. This is fairly uncommon, but will make a very loud, telltale noise. Good luck and hope this helps pinpoint some of your concerns!

[1990LTD]

oil pump and shaft etc are new, I always let it warm up before I start driving but not 100% normal operating temp.

what is SAE30? a particular brand of oil?


I don't think the fan is hitting the shroud, I think I would notice it. I hope I would anyway


Any way to check and see if my fan clutch has failed? I don't know if it's spinning with the crank or not


thanks a lot man

[gadget73]

sae30 is a weight of engine oil, probably not well suited for the cold. 10w40 might be better for you up there.

The knock is whats referred to as the lopo knock. Basically the main bearings are worn out and you hear the crankshaft slapping around until the oil gets to the bearing and cushions it. The bearings in a motor don't actually make contact with anything. The crankshaft and connecting rods ride on a film of oil between the bearing surface and the crankshaft. When the bearings get worn away, the clearances open up and the oil runs out when the motor sits, hence the knock until it pumps up again. There isn't anything you can do about it short of rebuilding the motor, so as long as its making some oil pressure I wouldn't get concerned about it. The reason the bearings get beat up in these motors has to do with the firing order. It puts two cylinders at the front of the crank in sequence and over time the #2 main bearing tends to get worn out. The HO and 351 engines have a different firing order that puts the sequential cylinders at the back of the crank where the bearing is larger. Those don't develop the knock.

[1990LTD]

ahh, I think I understand. thanks.


A HO modded lopo wouldn't develop the knock? Would there still be something "left over" from the life it lived as a lopo?


I actually don't know what kind of oil pressure I'm making. I have the gauge in my gauge pod, just not the sender and adapter to run it

[jayh]

could be bearings, piston slap, or a sticky lifter

noises are near impossible without hearing them in person

[gadget73]

HO converted lopos that had a knock originally still have a bit of noise to them. Once the bearing is worn out, its always worn out. It does tend to be a bit less obnoxious though since its not stressed in the same way. The cast pistons also can make a knocking sound until they warm up and expand in the bore. This is called piston slap, and its caused by excessive clearance between the cylinder wall and the piston skirt. Cast pistons expand more than forged, so they tend to be sloppy when cold, and it makes a noise. My S10 has been doing that for 9 years now and its never gotten any worse.