RPM's Rise During Decel/Overheating

[EDM95]

So this is what is going on ok when I start the car it is ok but then when I drive the car maybe down the road the rpms just start going up and then the car gets loud when I slow down makes a sound from the exhaust for example like vroom vrooom vrooom vrooooom.
So the rpms just keep going up and not down and into gear and then the water starts to boil also I have an oil leak but not sure where from. What could this be? I am going to pull the head but would that have something to due with the car not going into gear?

 

[TOONAH]

It sounds like your engine is misfiring while de-accelerating. How many miles on the motor? If it is a 7 bolt 4G63, the chances are that there is excessive crankshaft endplay.
The valves are probably shot and you may have a blown head gasket.
The best test you can do to verify the integrity of the engine internals is a compression test.
With the engine hot, all four cylinders should measure between 130-160 psi.
The gear shifting problem may be un-related and seperate to your other problems.
If the car has over 130K miles, it needs a complete rebuild. If you are not a DSM enthusiast, pull the motor and get a stock rebuild kit, replace the oil and water pump, main/rod bearings, new tensioner, timing belt, pistons and rings. New clutch kit. Have the head reconditioned. Should be able to do all that for $1000.00. Keep it all stock.

 

[EDM95]

It's a 420a and I did a compression test.
#1. 145
#2. 145
#3. 135
#4. 135

 

[rush2252]

Ok I get that its overheating and you have severe idle surge.. what is the part about going into gear? It is a manual and wont go into gear whenever you downshift?

Idle surge.. Check the TB for vacuum leaks could be leaking TB gasket or intake manifold gasket. The 420s are also bad about the IAC motor going bad. Try removing it and cleaning it with carb cleaner see if that helps.

As for the overheating is the water pump new? Have you made sure that the coolant is completely full.. i.e ran the car with the radiator cap off until the thermostat opens and made sure the system isnt air locked. You might check the thermostat as well. Remove it completely and see if it stops over heating.

Are your cooling fans coming on at all? If not try turning on the A/C this should kick on the fans manually as opposed to them being switched on whenever you reach operating temps.

Hope that helps. Although I now own a turbo model I could work on a 420a blindfolded. I have rebuilt several and flipped them for quick cash.

Good Luck,
Kolby

 

[Fotowntalon]

It's a 420a and I did a compression test.
#1. 145
#2. 145
#3. 135
#4. 135

those numbers seem really low? was the car heated up when you did this? and did you have your TB opened up or anything like that?

 

[LD25Delta9]

A few things. Number 1: You have a vaccum leak after the TB. Most likely originating from a hose. That's why when it's cold it's cool. But, as soon as hit gets warm down the road it starts a pinhole leak. Do a smoke test to find it.
Number 2: You comp readings are scary. If you did it when cold, do it again warm. If you come up with the same numbers, do another comp test, but add a teaspoon of oil into each cylinder before you test. That'll tell you if it's your rings or you valve stem seals. If your comp. goes up with the oil added, it's your rings. You should always do a comp test with the engine warm. Not ice cold or blazing hot.
Number 3: If you had an air bubble in the coolant system it wouldn't overheat. You car just idles real funny like. Only completely remove your thermostat to test if that's your problem. If you run without one your system never has a charge that it can store in your radiator and cool down before letting into your block. It'll just continue to cycle your coolant until it's all the same temp. Ultimatly raising engine and underhood temps. That's bad.

 

[EDM95]

It's an automatic and basicly when I go in drive the rpms just start going up toward the red line not kicking into gear. The coolant just boils but the temp gauge is normal and the coolant just keeps going down but I don't see it leaking and I know I put more than enough coolant in the car. The comp test I did do that when the car was warm.

 

[rush2252]

sounds like torque converter and head gasket isssues.



The theory on removing the thermostat was to see if it were stuck closed, therefore it would cause it to overheat I assumed the OP knew that.

 

[EDM95]

torque converter? Where ius this at and how do I check it?