1979-1993 & 94 Conv [Subscribe to Daily Digest] |
Members do not see ads below this line. - Help Keep This Site Online - Signup
The car: 1982 900 Turbo sedan, 25th anniversary edition, 175k miles. All electrical, emmision and APC components have been checked, cleaned, and timed properly. No vaccum or manifold leaks. Timing set at 20 BTDC with properly functioning vaccum/retard. Air fuel ratio is normal. I use only premium gas. The only modification has been installing a 1987 intercooler with all the stock tubing.
Here's the sitch. I'll first give you an ambient temperature of 70 + degrees. Once the engine has initially reached normal operating temperature after sitting all night, it works beautifully. Boost will effortlessly achieve the stock maximum range of 8 psi with no pinging. But after that initial warm-up and a period of driving normally for 20 or 30 minutes while the complete engine (intake manifold, turbo unit, engine compartment and intercooler) has reached it's respective warm or hot operating temp - that's when the pinging begins. Of course, the warmer it is outside or the harder I drive, the shorter the time until the pinging.
The problem is that I notice it where I wouldn't expect. I can understand hearing it while accelerating hard and especially in the higher gears. But where I don't expect it is when it happens in every gear beginning around 2500 rpms while not accelerating very hard at all. In fact, if I just hold it at 2500, regardless of the speed for that respective gear, I hear a mild pinging. If I accelarate slightly, it goes away, but then if I hold that rpm (2800, 3000...), the pinging returns. It's most noticable while driving along at 60+ mph on the freeway.
First the back story. I bought the car used from a previous owner who had no interest at all with maintaining the car's vital components. I like to say he tried to kill it with negligence. With several major oil leaks, the engine was coated with oil and dirt. Loose vaccum hoses everywhere. Frayed wires. Oxidized connections. A ruptured distributor advance unit diaphragm. And despite that, the car would fire up and purr. I had to buy it and return it to it's glory.
Once home I was stunned to find that the air filter hadn't been changed since probably the Reagan years. The filter itself was oily black and caked with dirt, and was actually sitting in a deep pool of oil at the bottom of the filter box. The 3/4 inch blow-by gas vaccum hose (from the valve cover to the air filter box) was FILLED completely, literally choked off with congealed hardened oil. You have to drive a very long time with a clogged air filter to have your engine suck that much oil out of the valve cover and harden inside the hose that way. Discovering all that, I was all the more impressed that this motor actually fired up. Almost brings a tear to your eye, kinda like the movie Memphis Belle where that plane shouldn't have made it home, but did.
So my thinking is this. With an engine run in that poor condition for so long, deposits within the cylinder head must be considerable. I've read here that one source of pinging is anything which may cause a hot spot within the combustion chamber. When I pulled the intake manifold for a cleaning (the first week I owned the car), I did notice excessive oil and carbon deposits in and around the intake ports, and especially on the inside surfaces of the manifold. I would guess the cylinder head looks the same.
Is that the source of the warm engine mystery pinging? Regardless, I am planning to pull the head for a cleaning and a new gasket.
, Mon, 28 May 2001 23:02:22
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
