SC300-95-TMM

Well I am finishing up my 120k or so PM on my newly purchased SC300 5 speed. Changed the following:

Plugs
wires
Cap
Rotor
water pump
timing belt
timing belt idler pulley
thermostat
upper radiator hose (any one got factory clamps for sale?)
serpentine belt
Fuel Filter (Don't get me started!)
and Flushed all fluids


When I purchased the car I drove it around the block for say 15 minutes and it ran fairly well. Engine idled smooth with no miss. It had a new clutch put in, battery and alternator just recently. I did notice a slight vibration during revving but paid it no mind. Just thought it might need a tune up. Well loaded it up and drove 10 hours back with it. I then took it around the block at my house and then proceeded to drive it up my steep drive way. Used a little too clutch and boy did that make a stinky smell. Kinda thought it was just a little to much gas and I dragged the clutch I hope!!? Smell lingered for a good while in car though.

Well the point with the vibration is I think I might have found what it is. I ran a compression check before I put the plugs in and here is what I found.

Cylinder #1 = 145 psi
Cylinder #2 = 120 psi
Cylinder #3 = 140 psi
Cylinder #4 = 155 psi
Cylinder #5 = 145 psi
Cylinder #6 = 155 psi

I did notice that the plug wire at number 2 had been damaged at the plug to boot end. Might now have a washed cylinder?? Of course this is not what I want to find out after all this work is that the motor might need to be rebuilt. I have not driven it enough to see if it uses oil, Does not smoke on startWhat is the nominal compression for these motors and what is the acceptable limit?? PIcs of plugs below. They look decent with no actaul burnt oil appearance. Any Idea?

SC300-95-TMM

plugs #1 thru #6 (left to right). May be hard to see

SC300-95-TMM

Well I guess a Leak down test is in order in a week or so once I drive it around and work any bugs out.

vipsoarer

the plugs look like your fuel mixture is good and ur not fouling the plugs...id assume that with that big drop on cyl 2 that your gonna have to get some new rings on it....but like u said a leak down will be ur best bet. good luck and i hope it isnt anything too costly.

SPORTcoupe

iTrader: (2)

Did you test # 2 a second time to make sure?
The plug on #2 looks prefectly fine.
If the plug hadn't been firing, or even missing occasionally, you'd notice a difference.
Kinda odd.
Leak down test is definitely in order.

Good luck.

~Alan

EDIT: As for nominal compression, since stock is 10:1 it should be between 145 and 155 psi

SC300-95-TMM

Yeah leakdown test is in order. It ran smoother since the pm upgrade with new parts. I will recheck next week and see if it is still low. Thanks

96sc3

iTrader: (1)

hi , im curious in what a leak down test is?
thanks.,.

SC300-95-TMM

It is a test that determines at what rate the cylinder "leaks" down under a constant air charge. You apply a low pressure air charge to the cylinder in question and determine first if you hear any air coming out of the valve covers. Means the rings are worn or valve guides are bad and causing excessive blow-by. If air comes out of intake, possible intake valve seat or valve failure. Oh and if air comes out tail pipe, then we got an exhaust valve or seat in question.

Some leakdown tests are more in depth by checking at what rate the cylinder will leak down in. Say 50 psi what put into cylinder and it takes say 30 seconds to leak down. This rate (psi/sec) is the compared to a standard and it will determine if the motor is good or time for a rebuild.