Coolant leak
#1
Coolant leak
I have a 88 S4 with a coolant weep/leak from the lower front r/h side of the engine. The PO replaced the TB and water pump 6k miles ago. I’ve read that one of the tensioner set bolts has to have sealant on it as it goes into a water gallery. Is this the bolt?
#2
Addict
Rennlist Member
Rennlist Member
Join Date: Oct 2003
Location: Gone. On the Open Road
Posts: 16,561
Received 1,682 Likes
on
1,092 Posts
If you are SURE that the liquid is coolant and not oil from the tensioner (smell it) then:
Rent a coolant system pressure tester (from Autozone, etc.) so that you can pressurize the coolant system with the engine cold. Test your reservoir cap first and use no more pressure in the system than the pop-off pressure for the cap. If the cap holds no pressure then replace it(**) and pressurize to 8 or so PSI(*).
Then use your eyes, inspection mirror, etc., to find the leak. You may have to do some cleaning. Leaks in that area will be either hoses at the water bridge or the pump.
(*) The reason to limit the system pressure to the cap's blow-off pressure is to ensure that you are not pressurizing the system in excess of the pressure that it normally sees. If the cap is dead or popping-off at less than ~10 PSI then a) your cooling system isn't going to work as well as it should and b) you might stress other parts of the system (e.g. radiator end-tank seals, etc.) if you use too much pressure.
(**) If your cap holds no pressure and you replace it with a new cap that holds to the spec 12-14 PSI then you run some risk of 'discovering' other leaks.
Good luck.
#4
Thank you for the response guys. I'm sure the leak is coolant and not oil. This is what I've read :"Remove tensioner idler spindle from water pump (nut that threads into the pump — it does not hold the pump onto the block but it does open into the water-jacket, so some coolant may drip)"
#5
Rennlist Member
It looks like you have the blade type connector on the tensioner that runs from the pin to the wire that goes through the belt cover. I would get the braided wire connector because the type you have is prone to break from twistage (sic). I thought they had phased the blade out by the time your car was built.
#7
Addict
Rennlist Member
Rennlist Member
Join Date: Oct 2003
Location: Gone. On the Open Road
Posts: 16,561
Received 1,682 Likes
on
1,092 Posts
The shoulder bolt that fastens to the pump and around which the stock tension roller carrier (tensioner idler spindle) rotates is not a bolt that secures the stock tensioner to the block. Your original post and finger describe and point (respectively) to a bolt that secures the (stock) tensioner to the block.
None of the four bolts that secure the (stock) tensioner to the block penetrate the water jacket. One bolt hole, sometimes, depending upon how deep the hole was machined, penetrates slightly into the cavity for a head bolt and thus can sometimes weep a little motor oil.
The shoulder bolt that screws into the water pump does penetrate the water jacket.
Trending Topics
#8
Addict
Rennlist Member
Rennlist Member
Join Date: Oct 2003
Location: Gone. On the Open Road
Posts: 16,561
Received 1,682 Likes
on
1,092 Posts
I thought they had phased the blade out by the time your car was built.
Part number 928 607 110 00 which can be obtained through whatever parts vendor you use (which should be one of 928 International, 928 Specialists or 928sRUs.)