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Car jerks badly when cold

pippo

Member
112
7
18
Florida
1987 Sunbird GT non turbo, when cold engine, and accelerating, the car jerks back/forth, struggling at about 3000 -4000 rpm's. manual transmission. But after say, 5 minutes, as it warms up, problem goes away. Recent cylinder head replaced, but leaking oil at camshaft carrier, and blue smoke coming out of tail pipe. Head gasket blew with coolant spewing everywhere, before head gasket replacement.

I dont think the oil burning should be the cause, do you? Maybe head gasket was not put on right and coolant is seeping into cylinders when car is shut off, sits overnight, and upon startup car runs rough because of coolant mixing with fuel(?). But shouldnt that be spit out immediately, and not for 5 minutes?

I checked the OHMS on both temp sensor and air temp sensor inside air filter housing, both checked out OK.

Thanks.
 

92 Sunbird LE

Well-known member
2,004
29
48
Salinas, Puerto Rico
Sounds like the coolant sensor, or fouled plugs. ( Autolite platinum plugs can run while fouled better than others)

A radiator pressure test will determine if coolant is leaking into the cylinders, and a compression test will tell you where the oil is leaking.

Try Seafoam in the tank or letting the car warm up a while before driving till you can check the other things above.

Doug in P.R. šŸ˜Ž
 

pippo

Member
112
7
18
Florida
Thanks, Doug. Seems obvious about coolant sensor. I should have explained clearer that I tested the coolant (temp) sensor and it checked out fine as far as resisitvity values. . No codes as well. Plugs are clean (removed all during compression test). Did compression test and got 175 psi on all cylinders. But did not do the "wet" test where you repeat test with a teaspoon of oil. At 175 psi not sure if it even is an issue.

Drained the oil and found no pooling of coolant at bottom of the oil catch pan. I rented an expensive rad pressure test kit and not one fitting fit my sunbird's huge coolant housing cap. Have tyou ever noticed that? Why we have such a huge cap(?).

Anyway, yes, I will warm up car before driving it.
 

pippo

Member
112
7
18
Florida
Just did the wet test, added a bit of oil and retested, and got 195 psi. So, 175-180 psi dry, 195 wet. Sound like the rings are still in good shape?
______________________________
 

92 Sunbird LE

Well-known member
2,004
29
48
Salinas, Puerto Rico
Valve seals changed when head gasket put on ?

Mine burns a little on start up or full throttle ( plus the oil pan and valve cover leaks a little at just about 150k miles now )

Radiator has a cap on the driver's side .( Not on top , on the side of the radiator)

Doug in P.R. šŸ˜Ž
 

pippo

Member
112
7
18
Florida
yes, all new parts/seals on head, including valve seals. Came with the set. Going to repeat the entire head job, not sure when. Not so bad. Costs little. Wont bother removing intake, or dismantling even the valve cover. Take it off with the head and camshaft carrier. Anyway, I will let you guys know what happens after!!

have a good weekend.
 

pippo

Member
112
7
18
Florida
Figured it out! Recently I installed a new ignition module. The 3 pin connector (closest to driver) had the plastic insulation all rotted/cracked, so I simply pushed back in the 3 pins/connectors. Thats when the jerking started! I should have noticed immediately! So, I removed the dist cap, and on bench, I carefully pulled each pin and wrapped with elect tape. Pushed all 3 back in and drove car with cold engine, and jerking disappeared! Wow, so glad. Thought I would share this.......
 
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