Hi Guys,
Audi A4 Avant 1.9 TDi AJM engine
Lets start with the story: 2 weeks ago I lost all my coolant due to the bottom hose coming off. Managed to limp to a service station where it was reconnected by the AA man (UK recovery service). Since then the car has been overheating if I go above 70mph. For a while the water temp was 105 (with 90 at straight up - the normal temp) and oil temp was just over 100. Now the water goes right up to 115deg if I go above 70mph.

I have changed the oil, replaced the coolant, changed the t-stat (checked it opened just before boiling in water - rated at 87deg) and tried all of the suggested ways to burp the system. The heater runs hot and the pinhole leaks coolant if I pull the hose partly off. The coolant level is constant and there is no 'mayo' in the oil or bubbles in the coolant reservoir. I flushed and back flushed the radiator (it ran clean both ways).

The only odd thing I can find is that the bottom hose is always cold (not even warm) even when the top hose is too hot to hold . . . this implies that the rad is not flowing . . but it flushed no problem so can't be blocked . . can it?.

I am totally stumped on this one people and would love to find out what the issue is before shelling out my hard-earned readies. I'm pretty handy at doing any work diy but don't fancy pulling the front end apart for no reason.

. . . . and another thing - were the hell is the water (coolant) pump on an ajm motor. The manual shows it under the aux belt tensioner but its defo not there! Any help would be lifesaving here guys . . I WILL beat this. :0)

 

So you're saying there is a small hole in one of the hoses? That wouldn't let the coolant system pressurize and could be constantly letting air into the system. I don't know how your engine looks, but does the bigger hose from the coolant tank go down towards the bottom of the radiator?

 

40 views and 1 reply . . . must be a tougher problem than I thought! :0)
thanks for getting in touch A4 2000.

No, My ambiguous English I'm afraid. There is a small pinhole in the LH heater hose at the bulkhead which is normally slid over the heater stub inlet (and therefore the system remains sealed) but it can be revealed by slacking off the hose clip and pulling the hose part way off the stub to bleed (burp) the system.

The radiator bottom hose goes to the engine via the t-stat, and the large er outlet from the coolant res connects to the bottom hose as it enters the rad.

 

Ok, well that sounds similar to my setup then. Just as an experiment, try running without a thermostat and see what happens under the same conditions. Sometimes thermostats can be defective. Overheating one time can damage the wax element inside them. If you are still overheating, your water pump might be the problem. That's something you'll probably have to take apart the front of the car for.

 

Are you sure you didnt put the t-stat in backwards? The element goes toward the block. I know it sounds stupid but I gotta ask. Thats the only thing that would separate the system like that.

 

Hi Guys,

Thanks for the replies . . . I bit the bullet and went for it, stripped down the front end. the pump is under the timing cover driven by the timing belt - i only changed that 2 months ago . . shoulda done them both at the time :0( The impeller shaft had stripped its splines so the cog was spinning but not the impeller
46 quid for a new pump and 6 hours in the sunshine later, all fixed.

cheers Mike

 

Wow, a water pump that only lasted two months huh. Was it the one with the metal impeller? Glad to hear you got it fixed.

 

I think he said he did the t-belt and did NOT do the waterpump while he was there. Let that be a lesson to all of us....

 

Oh ok, yeah. I agree that something along the lines of a Blauparts complete timing belt kit is worth while getting to avoid something like this happening.