Hello Everyone,

I have a 1997 J30t with about 110,000 miles. The water pump is 2 years old, and the timing belt roughly 5-6 years old. The car was in the shop several weeks ago for a coolant change. Less than a week later, I had a coolant leak, which was later shown to be caused by a crack in an upper radiator hose. My shop has had the car while the upper and lower hoses came in. Now my shop tells me that the one-use nut on the water pump has come off, and they want to replace the pump. I have a new OEM pump, and I ordered a timing belt from Scottsdale (since it makes sense to do both jobs together). However, I have two questions. One, why did the hose fail only a week after changing the coolant? Coincidence? Two, why did the nut come off just now? Coincidence again? The old pump may have been a Bosch.

I searched, but I did not see anything in the threads I found.

Chris

Perhaps the coolant hose was marginal and they disturbed it during the flush? If they did a chemical flush rather than just a drain and refill, it may have loosened some gunk that was blocking the hole in the hose. While you're into all of this I would replace your thermostat with an OEM new one if it hasn't been done in the last year or two.

No idea on the pump, but if it was aftermarket I'm not overly surprised.

Heath
Modified by Q451990 at 3:12 PM 1/28/2010

Heath,

Thanks; we are changing the thermostat also. How often should I change the coolant and thermostat? I drive about 8,000 miles per year. I use distilled water. Anything else I should know?

I usually put OEM parts in, but my shop ordered a pump before we had everything settled. I had ordered the OEM pump more or less simultaneously, and that is why I have one on hand now.

Chris

I try to flush all of my fluids annually... maybe overkill, but way cheaper than hard parts. You're certainly on the right track with distilled water. I would make sure to use a silicate-free coolant. I get the Dex Cool orange and mix it in a 60/40 (40% coolant) blend - which is plenty of freeze protection for our area.

By the way, if you're buying your own coolant and taking it in, Prestone has a BOGO rebate right now... http://prestone.com/rebate/?productID=31 I had to right click the link to view the .pdf and click "save target as..." it wouldn't open in-line for some reason.

Heath
Modified by Q451990 at 12:00 AM 1/29/2010

Remember you have a cast iron block and aluminum heads so things are very critical vs an all iron or all aluminum engine.........in selecting the correct additive package in the AF. Depletion is faster due to disimiliarity.

Any recommendations for this combination? I forgot about the J's iron block...

Heath

Does the iron/aluminum business relate to the question of the antifreeze being free of silicates? it sounds as if one should be concerned about corrosion, but I know just enough electrochemistry to be dangerous.

Chris

Chris Halkides wrote:Does the iron/aluminum business relate to the question of the antifreeze being free of silicates? it sounds as if one should be concerned about corrosion, but I know just enough electrochemistry to be dangerous.

Chris

I believe that it does - but I know even less about it... Might be worth getting one of the "safe in any engine" coolants barring more advice from Q45Tech.

Heath

I went over to another forum that specializes in oil discussions - http://www.bobistheoilguy.com

There is a coolant sub-forum there and the discussion, like most there, seems to give more questions than answers... lots of opinions. As best I can tell, Zerex Asian might be your best bet. I read the owner's manual for my truck, that also has an iron block and aluminum head, and it specifically warns against using "orange" antifreeze - so I think I would stay away from dex cool for this application.

That said, I used it in my old truck, a '97 Hardbody, for 7 years and had no problems with it. Also Zerex's site recommends their Dex Cool for Nissans built after 1996, but there's no mention of their Asian coolant anywhere on the chart, so I suspect that chart was made before they introduced it... All very confusing.

I would love to hear more from Q45Tech on this as well.

Heath
Modified by Q451990 at 12:20 PM 1/31/2010

My mechanic suggested Prestone G, but the Prestone site does not seem to use the letter "G' in its products. Not sure, but Prestone seems to be for all engine types.

Chris