Stumbling/hot no-start problem. When '88 735i gets warm it won't start until engine cools down(20-25 minutes?) Engine turns over but wont run, it acts like the timing is off(piffs and sputters and acts like its flooded?) After it cools down, it'll start but runs rough like it's got a couple fouled plugs!? Any ideas? I need some help PLEASE!!!! Thank You, Scott

IF there was a problem with the engine then running it for such a long time would have revealed faults. Idling an engine for such a long time is not good for an engine as it is operating at reduced oil pressures with out proper coolant circulation around the block and heads . Better to take it for a 1/2 hour run. If it is an efi engine then run the fault codes as a check as well. otherwise it should be good
It would be better if you told us what the boy did wrong so that a more exacting diagnosis can be made.

If I crank the motor while it is st ??????? Probably ignition module . When it shuts off check for spark .

Someone will need to figure out if you are dealing with a no spark or no fuel pressure issue to proceed.
Could be a long list of things including relays and electrical components.

Try getting your transmission solenoid replaced. After I got mine replaced it ran fine after that. That's the exact same thing my Lumina was doing.

Main relay was problem with my 91 civic. Not a problem since replacing. Seems they tend to get hot.

crank pos. sensor or maf sensor ck. the fuel press reg. also

Are you sure that the spring side of the thermostat is toured the engine/ look for a bleeder near the top highest spot in a line or hose that may be able to release the air it may even be near the water pump side.on some water pumps for the ford's the pumps will bolt on and look almost the same but the fins on the impeller are the opposite.clock wise instead of counter clock wise or vice vars. you my wont to check with your parts supply store to see if that is possible.hope this helps give you some ideas.feel free to ask again if you would like any further assistance.thank you for asking fixya . Have a Grate Day

It is most probably the problem with blend door or blend door actuator. But just in case I would suggest to follow the entire procedure:

First you have to identify what causes the problem.
To do this you have to:
1) When engine is cold check the level of coolant. If it is low fill it up.
2) Start engine and check if engine reaches regular temperature. If your engine is not heated enough it means your thermostat does not work properly and should be replaced
3) If engine temperature is normal, then check the temperature of pipes that go to/from heater core. These pipes are located up the fire wall (easier access is from the passenger side). If pipe/pipes are cold (even engine is warm) it means you heater core is plugged and should be flushed. Keep in mind, flushing the whole cooling system is different from flushing heater core.
4) If pipe/pipes are hot/warm, turn off the fan, switch controller to the hot position, wait for 3-4 minutes and turn on the fan. Note if the cold air blows first or warm air blows first but it cools down in 5-10 seconds. If the air blows cold than it is most probably the problem with blend door or blend door actuator.
5) If air blows warm first and then cools down, then while running engine and remaining the transmission in PARKING position, press on the gas pedal until your engine reaches 3,000 RPM. Check if your heater blows warm/hot air. If it does, then your water pump does not work properly and should be replaced. If the air still cold, I would suggest flushing the heater core.

First you have to identify what causes the problem.
To do this you have to:
1) When engine is cold check the level of coolant. If it is low fill it up.
2) Start engine and check if engine reaches regular temperature. If your engine is not heated enough it means your thermostat does not work properly and should be replaced.
3) If engine temperature is normal, then check the temperature of pipes that go to/from heater core. These pipes are located up the fire wall (easier access is from the passenger side). If pipe/pipes are cold (even engine is warm) it means you heater core is plugged and should be flushed. Keep in mind, flushing the whole cooling system is different from flushing heater core.
4) If pipe/pipes are hot/warm, turn off the fan, switch controller to the hot position, wait for 3-4 minutes and turn on the fan. Note if the cold air blows first or warm air blows first but it cools down in 5-10 seconds. If the air blows cold than it is most probably the problem with blend door or blend door actuator.
5) If air blows warm first and then cools down, then while running engine and remaining the transmission in PARKING position, press on the gas pedal until your engine reaches 3,000 RPM. Check if your heater blows warm/hot air. If it does, then your water pump does not work properly and should be replaced. If the air still cold, I would suggest flushing the heater core.

no fan comes on when engine cold start up .but it will come on when you turn on air conditioning or defrost on .if engine idling a while when temp get 190 degree the fan will kick on.if over heating you got air in system .wait until cools check coolant add more .crank engine let it idle few. minutes when start warming up turn off engine wait a while before removing radiator cap so you wont get scald.add more coolant .crank it again starting warming up turn off engine wait a while .add coolant .keep doing this procedure until your coolant stop dropping off .if you do this more than 6 times you got a leak some where.check crank level for signs.if oil level higher than normal.if everything looking good.when engine cool make sure add coolant to over flow jug cold level mark.