Should I do some preventative maintenance on the cooling system?

I’m doing some winter prep on my ’99 4.0L Auto, 99,850mi, 3” lift. I got the XJ w/80,000mi almost 2 years ago.

I’m flushing the cooling system for the first time since I’ve had it. I used the 7 hour Prestone stuff, left it in for two days for good measure, then used the 15 min stuff, left it in for an hour, now the water is clear, and the engine is running smooth.

I have new hoses, upper and lower radiator and the two heater hoses. I’m planning on replacing them, however I also have a new water pump and thermostat housing, I got them off of Ebay, from Mako Offroad, they claimed to be “High Flow”.

My question is; would you replace the water pump and therm housing? On the one hand the engine has almost 100,000mi on it and I figure I would rather replace it now while it’s reasonably warm, then have to do it when it’s 3 degrees out in the middle of feb. But on the other hand “if it ain’t broke, don’t fix it” comes to mind. The gaskets are good, no leaks, and the pump seems to be fine, so I would hate to monkey with it just to put in an inferior part that I have to replace again in a few months.

What do you guys think?

Personally, if you've got the parts and have the thing drained...I'd swap them out. Your not really that far away. My pump went right at 90,000 so you might be just around the corner.

I agree, change em, I flush my stuff twice a year, normally right before it gets nasty cold, and then in the summer. that way its nice and done and i know im good in the nasty bad weather. besides no real harm in taking it apart to get a better look at whats inside!

I hear what you guys are saying, that's what I'm thinking.

Anyone get one of those "high flow" water pumps from Mako Offroad from Ebay? I guess I'm just looking for someone to tell me this thing doesn't suck. One of the things that concerns me is; in the FSM it says I need a reverse flow pump. It says there should be an "R" stamped on propeller, which this dosen't have, although it looks the same otherwise.

If I had a part I trusted(OEM) I wouldn't think twice, I'm just worrried about this thing being a piece of crap. I know the factory just farm out stuff like water pumps, but I figure they find someone they trust for the sake of not having to recall them.

jmsull, where in chicago?

i am in ravenswood area, the northern end of the brownline.

kndrewa said:

jmsull, where in chicago?

i am in ravenswood area, the northern end of the brownline.

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In Forest Glen/Sawgunash, just north of where 90/94 split, Cicero and Foster.

So I just went to Ebay to look up Mako to contact them, it looks like they aren't there anymore, that's a good sign

High flow just means they bored it out, supposedly you need a "hi flow" thermo housing when doin a hi flow pump, which you have.

I would do that, also be sure to run a factory temp thermo, and drill a burp hole, and be sure to thoroughly burp your engine

Personally I don't like any of the high performance pumps out there, my preferences run to new dealer OEM pumps or NEW pumps from a reputable professional supply store like NAPA or CarQuest that supply the local shops. I don't use NAPA much because of their bankers hours, the local car quest stays open till 6 or 7 which is generally when I get in the area. As for the tstat housing, I've never had an issue with my stock one thru 3 or 4 thermostats, I do use dealer OEM tstat and gasket as well as dealer OEM pressure cap of 18lbs, seems all the aftermarket books call for 13 or some such low pressure.
If you have the whole nose apart I'd do the tstat, hoses, waterpump, belt, both idler pulleys [pick up a krikitII belt tension gauge at NAPA for $14, handy], pressure cap, use distilled water and when you remove the heater hoses don't pull them off, slice them with a razor or xacto knife then peel it off. Break or crack one of those bungs off the heater core and you got big troubles.
I also would never use any of the 15 min flushes, thats like using a sand blaster, replacing the water pump now is probably a good idea, every time I have used the 15 min flush the seal and packing in the pump usually goes in short order. The 7 hour flush is more a chemical reaction that breaks down the crap that builds in the system, but it does it gradually over that time period and resuspends the stuff in the coolant, the 15 min flush more or less blasts it loose. Just my opinion.
One other thing you might want to do while the nose is all apart, pull the radiator and clean out the fins, then get any leaves or bug parts that have gotten between the rad and the condenser, spray out the condenser too from the back side to get all the bits and pieces out that it has had rammed into it thru normal driving...

Yes, autozone lists the radiator cap at 13 psi......that's too low.

Everybody told me stock cap was 16 psi, however.

Blaine B. said:

Yes, autozone lists the radiator cap at 13 psi......that's too low.

Everybody told me stock cap was 16 psi, however.

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Yea, just checked my stash, 16psi for the OEM caps.

well I just replaced everything, hope it all lasts for a while.

RichP said:

Yea, just checked my stash, 16psi for the OEM caps.

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It was probably you who told me before too. Thanks!:us: