Monday, December 11, 2006 - 10:29 am, by: John Jantzen(Taslex)
I bought a new water pump from Toyota the other day (sorry Neil - I couldn't risk the slow Aust Post at this time of the year). They supplied me with P/N 16100 50023, which in these forums is said to be the correct pump. However, on comparing the old pump to the new one, I found that the welch plug on the old pump had been replaced by a drilled passage which extends at 45 deg from the pulley bearing to a rounded housing,which looks like it should seal to something, but on my engine at least there is nothing for it to mate to. The housing just sticks out over the mating surface for the rest of the pump. When I realised this was going to happen, I blew air through the hole to see where it led to, and if I needed to block it before I used this pump on my engine, but it seemed to only come out around the outside of the pulley, so I concluded that the passage's purpose was just to route drips from a leaky pulley seal over to the side of the timing belt case, where they wouldn't fall on the belt and crank gear/pulley. Because of this deduction I didn't block the passage up, although I was tempted to. I put the new pump onto the engine, and filled that part of the cooling system to see if anything came out of the passage. Nothing. I turned the pulley by hand many times to see if that provoked a loss of coolant. Also nothing. I put the car back together, filled the cooling system totally using the bleed screw and the bubble tank, and started test driving. All seemed well on my first test drive (about 10mins under 60kph), but on the second one (about 20mins at 60-100kph) a small puddle appeared under the car in the general vicinity of the timing belt case. I must admit that I did park the car facing downhill after the second test drive, so it may just be splashed coolant from overfilling at the bleeder screw running out from wherever it was resting. I haven't had the time to repeat the tests, but I'm posting this just to ask the question:- Should you block the drilled passage I refer to when using a 16100-50023 water pump on an old v8? An answer to this will at least tell me that I either do or don't definitely have to repeat this rather long job!
Monday, December 11, 2006 - 10:48 am, by: Peter Nitschke(Pen)
John, I am pretty sure that the new pipe is just a drain as you suggested. There was a post about it ages ago, but either I just can't find it or I am wrong.
Monday, December 11, 2006 - 12:53 pm, by: John Jantzen(Taslex)
Thanks Peter, I hope someone's got a definite on this. I have found a picture on lexusextreme.com in the timing belt section that shows a new style pump being installed on a V8, and it does not appear to have been modified. A few words for anyone considering this job: it's not hard, just long (in my case 14hrs). If you download a pdf that's floating around from the shop manual, it gives you the sequence, but I think it is far too pessimistic. I doubt that it is necessary to unmount the air con compressor, alternator or PS pump. I reckon that removing the radiator could be avoided, but it's probably a good idea to do it for the safety of the radiator. I wasted nearly 2 hours on the air con compressor alone - the back bolt is extremely hard to reach (I took off the road wheel, and used about 500mm of extensions, plus a universal joint to undo this 14mm-head bolt). Placement of the CA sensor wiring (5 o'clock near crankshaft) is critical or it will foul the aircon pulley or the belt. (I had to redo the aircon compressor bolt-up because I didn't foresee a problem with this) The rope trick for immobilizing the crankshaft works beautifully. In this, you take out #1 sparkplug, and turn the engine until the piston is at or near BDC. Start threading a 2m length 8-10mm diameter nylon rope into the sparkplug hole, twisting it as you go so that it will wind into the cylinder. You then have a barely compressible but soft medium which stops the engine turning over. Considering the enormous forces acting on a piston + conrod when it reverses direction, I doubt that 200 ft/lb would be outside tolerances for these parts! Thank you, Freeman Tang (Cobra_Man) - I found this trick posted by you in the ALSC Archives from 2003. I easily loosened the crank pulley using a 1/2" drive 22mm socket on an "L" handle, plus a 1 m long piece of 1" steel water pipe as a breaker bar. I'm a little sceptical of the "starter" method of loosening this bolt - if you were unlucky it could burn out the starter motor and/or damage its geartrain - I've seen reports of this happening.
Monday, December 11, 2006 - 02:13 pm, by: John Jantzen(Taslex)
Thanks Peter, By the way, nice price on the pump! Toyota here (Hobart) wanted $175.38 inc GST, which I thought was not too bad, until I saw what you paid.
Monday, December 11, 2006 - 02:34 pm, by: Peter Nitschke(Pen)
Side note, I am currently replacing the top V8 overflow or bubble tank, and I am a bit shocked at how much grunge is sitting in the bottom part of the old one.
Cleaning the tank out should become part of a radiator flush job.
Monday, December 11, 2006 - 02:48 pm, by: John Jantzen(Taslex)
Mine's cracked, but I keep repairing it. How much do CMI want for one? I was hoping someone might have come up with an alternative by now, metal would be good!
Monday, December 11, 2006 - 06:15 pm, by: John Jantzen(Taslex)
Just drove home, parked the car, looked underneath - coolant dripping out madly from bottom of timing belt 'case'. What the heck has gone wrong? I'm going to have to pull it all apart again. aaarrrgh!!! I'm guessing about what I will find: 1. Cracked O-Ring on pipe into back of pump? 2. Leaking form-a-gasket on pump or piece of rubbish between pump surface and engine mount surface? 3. Maybe that passage should be plugged? 4. Defective new pump seal? 5. None of the above! Any other possibilities?
Tuesday, December 12, 2006 - 11:12 am, by: John Jantzen(Taslex)
Where's this welsh plug that's supposed to leak? Is it the one on the original water pump? I couldn't seem to see any other when I had my engine apart recently. Photo anyone?
Tuesday, December 12, 2006 - 07:58 pm, by: John Jantzen(Taslex)
Well, did some thinking on this problem, took the left hand distributor & pulley cover off to get easy access into the timing belt area, then ran the car, and had a good look inside at what was happening around the belt. Coolant was dripping madly off the pump drive pulley, , and continued doing so for some minutes after I stopped the engine. OK, coolant can't run uphill, and car is tipped up on ramps, so it can't be the gasket mating surfaces (which all looked dry anyway) or the back O ring. What about a defective pulley seal? Surely not in a new pump - also there's no coolant coming out of seal vent pipe (used dentist's mirror to check all this!) and it would have to run uphill, anyway, to get on the belt from the inner edge of the pulley. Then I noticed coolant sitting ON the belt where it runs under the pump pulley. OK, so coolant is running onto the pulley from above. Aha! I think we may have it! I poke a piece of dry rag into that inaccessible area on the belt cover under the thermostat housing base assembly. Comes out really wet. Got it! Once I removed the Thermostat housing base assembly, I found that the large O-Ring is actually very loose. I reckon that's the true villain! Fortunately I've ordered one from Toyota and I'll get it in a day or two! Thanks very much all of you who shared your expertise with me. I think my experiences with this job prove two things: 1) Replace those O-Rings! 2) Have a DAMN GOOD LOOK before pulling it apart and you may save yourself hours of work!
Oh, one final point - my original water pump was truly stuffed too - the first job was not in vain. There was about 2mm up and down and in and out clearance in the bearing - and you could see the coolant peeing out just turning the pulley by hand!