The project we are working on today is an overheating issue on a Volkswagen 4 cylinder. This would cover all 1.8 turbo models and 1.9 TDI. What we experienced with this vehicle is no overheating at ideal, but if you drive the vehicle 6 to 7 miles the engine temperature will start to decline. On this vehicle we knew that there was stoppage in the radiator, because it did recently had a colon system flush and we notice that there were no water leaks or coolant leaks of any kind.
Auxiliary fans were working correctly but the vehicle just seems to on the free way or any kind of driving after 6 or 7 miles the vehicles start to overheat. So let's see what we did to diagnose this project and then turnaround and do the repair.
After the run for a while our suspicions were that we had some kind of circulation issue. So we removed most of the engine cover and stuff so we can actually see the motor and what we did is we let the car warm up and we checked the upper radiator hose. Once the car was warmed up, the radiator hose was warm which indicated that the thermostat had opened. If the thermostat had not opened we would have a cold upper radiator hose.
So the next thing to check would be, is the water pump actually circulating water. well, in most situations the water pump wouldn't be a suspect unless we had a leak of the water pump. But knowing that the design of the Volkswagen water pump, we decided to take the intake hose off of the vehicle. This is the lower radiator hose that fits up to about an inch and a quarter fitting that goes just above the alternator. What we did with this hose is we took the hose off, connected another hose to it and ran the hose to a bucket and then started the engine once again.
Now if we would have had some kind of - if we would have had adequate circulation we would have instantly got a rush of water coming out of the lower part of this radiator which is this hose right here because we would be circulating water from the pump through the engine block out to thermostat into the radiator, bottom of the radiator would then dump into this bucket. We had zero circulation or we had no water pressure coming out of this at all which made us once again suspect of water pump.
An interesting thing about the new design of water pumps these days for these cars is many of the manufacturers are deciding to use a plastic impeller; a plastic water pump impeller that on pervious designs was made out of cast iron. The problem you have with the plastic impeller, the plastic is actually vulcanized to a little ring which then is pressed over the water pump shaft and what seems to occur with this plastic water pump impellers is they will break loose off of the inner shaft and that's exactly what happened to this water pump right here. Watch what happens.
The actual impeller that is supposed to be pumping the water is just free wheeling, so that created a situation why the vehicle would overheat after only a few miles of driving. The impeller was turning and probably a few weeks ago, it was actually still frozen onto the shaft or pressed onto the shaft somewhat better than it is now. But what has occurred here is it is totally free wheeled now, so there is no water pump pressure at all anymore.
So this vehicle went from a slight overheat to a gradual overheat till finally probably in another few days it would not have even gone couple of block without running into the rib. So this is the situation where when you purchase a new water pump you want to get a water pump that has a metal impeller, an iron impeller that is pressed onto the shaft and it can't break loose like this. In my opinion it is just a design flaw.
Now that we have discovered what the problem was replacing the water pump is going to have to be the solution. We have already removed the pump out of this TDI, but let's take a look what it is going to take to remove it. Typically there is a plastic shroud that covers the timing belt and the timing gears. This gear right here is a fuel injection pump sprocket, this gear right here is the cam sprocket. The situation we have got to remember is that we have to keep the timing relationship of the cam; the injection pump and the crank shaft the same. The crank shaft will stay put by just putting it at top dead center before you start the project.
Here is the components we are going to replace with this project. Your base project is going to be replacing the water pump. What we are going to select is a water pump not like the factory one that has the plastic impeller that has the plastic impeller that broke free on this TDI. We are going to replace it with a water pump that has a cast iron impeller which is pressed on and they have never come loose in my experience.
So you are going to end up with a better water pump. At the same time I recommend doing the timing belt, the tensioner pulley and the idler pulley. These two pulleys here are typically spinning at a higher rpm than the engine and the situation with these pulleys is, they have got a permanently packed bearing that is packed with grease one time from the factory which means htye are going to spend their entire lifetime with the lubrication that is in that bearing.
What you want to do is replace that at the same time you are doing your belt. Now in turn if you are doing a belt project I would also recommend doing a water pump project just in case if you were to have water pump leak then you will be doing these two projects in a staggered fashion. Do it once, you will save some money on the labor. Now we are going to go over back to the TDI and I will show you how to make a tool that will allow you to lock the cam sprocket and the engine pump sprocket without buying an expensive factory tool.
Here we are back at the vehicle so you can see the cam sprocket locking tool that we devised to keep the cam sprocket and the injection pump sprocket in a locked stationary position for doing this project. If you watch one of my other videos we have go the instructions on how to make this tool yourself. What it will basically do is it locks into two sprocket cogs on the injection pump and two sprocket cogs on the cam. We have also used the little white out here and marked where we are locked in. once you tighten the bolt; those two sprockets are locked down for good. If you check out one of my other videos you will see exactly how to make this piece from small parts you can buy from the hardware store.
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