Been away for a long while. 

Bought a 99 2.0.  The coolant was a little metallic when I looked at it, the rad fins were mangled in 2 spots I figured he had a water leak.  Saw a wet spot inside the fan shroud too, so I wasn't worried. 

Now the coolant is kinda scary, no loss of cool and and no loss of oil.  How bad are these engines for head gasket and timing chain failure?   

Biggest tire on an automatic before mpg gets bad?  Can it be driven with OD off to compensate for 31s?

Radiators on these trucks are typical plastic and aluminum OEM things that will eventually start leaking around the sealing surface of the plastic and aluminum OR the plastic tanks will just begin cracking and eventually leak.  Replacement radiators are available from the typical parts store chains.  AVOID the Murray brand radiators.  I went through FIVE of Murray radiators (I bought at O'Reillys) before I asked for my money back and then went to AutoZone or Advance Auto and bought their brand.  I can't recall the manufacturer of the one I got off of them off hand.... but it was of far better quality AND the core thickness matched the OEM radiator very well.  I'm still rolling on the one I bought from Auto Zone/Advance Auto. As I recall, it cost right around $215.

Both the 2 liter and the 2.5/2.7 V6 engines will (not maybe) develop timing chain issues when/if the proper oil isn't used during regular oil change intervals.  If you hear excessive chain rattle when starting up a cold engine, and it lasts more than a few seconds.... chances are very good the hydraulic tensioners are failing or have failed. When the tensioners fail, it creates excessive slack in the timing chain and it literally whips itself to death until it breaks. 

Also, on the 2 liter engines, there is a metal bracket over the chains of the cam gears that can wear from too much chain slap/vibration and break/fail and then the pieces will tumble down into the timing gears and chains = engine damage.

If you elect to replace the timing chain with a new kit, spend the extra $30 or so and put a quality chain kit in your truck.

Given that very few people stay up on the maintenance of their vehicles... and even fewer keep the documentation to prove they did... and that even if/when they do this documentation gets tossed or lost... it is a safe assumption the engine hasn't had the regular oil changes using the correct oil that is required.  It costs around $200 for a new, quality chain kit for the 2 liter engine.  If you can do the work yourself, then add a new water pump to the cost and it is a relatively inexpensive repair (although aligning the timing gears is difficult simply because the marking is hard to see while the engine is in the truck).  Have a shop do the work and you will be into the repair about $900+/-.

Wait until the timing chain breaks while you are cruising down the road and you can add another $400-$500 to the repair costs for the required machine work to the head and needed valve replacements, providing no more damage occurs.

I have 208K miles on my 2 liter and so far (knock on wood) I am still running the original head gasket. I think over heating is the major cause of the head gasket problems and this is usually from clogged radiators, failed or failing water pumps or bad thermostats.  I have probably jinxed myself by mentioning this now.

On the bright side, the 2 liter is a stout little engine, makes decent power and can be relatively trouble free when well maintained.  The same could be said of the V6 engines as well... I'm just a big fan of the 2 liter engines.  Pound for pound, I think they are the best engine for these trucks.  Sure, I'd like to have another 20HP, but that's what God created 5-speed transmissions for, isn't it?

235 tires work without killing the cruising ability.  You could probably get away with 30" tires with an automatic.  It may shift back and forth in gearing at cruising speeds though.  I ran 235s with stock gears for a few years and I really didn't notice any loss of mileage, although I did notice a loss of power.  Particularly in 5th gear.  I changed out my stock 4.62 gears for a set of 4.88 gears (that come in the automatic tranny equipped trucks like yours) and the 4.88s have given me all the mechanical advantage I had lost and just a little more while running 30" tires.  You could always upgrade your gears to 5.12s at some point in the future and do pretty much the same thing as I did and that many others have done as well.

Thanks for the heads up. It only has 97 thousand on the clock.  The last 15 months it has seen  400 miles a week on a mail delivery run.  I'll listen in the morning, it was warm already when I bought it.

The water pump is a bad item on these? 

As far as I'm aware, water pumps are not a common failure item, and given the fact that it is quite accessible (it's located on the side of the engine, away from the timing chains (unlike the V6), I wouldn't touch it, unless it was defective.

As far as I'm aware, water pumps are not a common failure item, and given the fact that it is quite accessible (it's located on the side of the engine, away from the timing chains (unlike the V6), I wouldn't touch it, unless it was defective.

I agree with Fordem on the water pump.  Being a '99, I was erroneously assuming it had close to 200K on the clock.

Intermittently while drivng I had oily antifreeze spray onto the windshield.  No sign of where it came from, just some water mark above the reservoir.   Finally when I got home I popped the hood again. While looking at the car,  leaning in of course, I got sprayed like a squirting gun.  Just a little squirting.  I'm looking at the rad and it did it again.  At a spot where there are some creased fins.  So now I'm thinking it's not oil but rad fix, which he assured me he never put into it.  Something happend,  the rad got damaged, I'm assuming the car overheated, he could not find the leak and just topped it up thinking missing fluid is head gasket.  Head gasket is probably bad now anyways. 

Are these 2.0 engines known for head gaskets?   If I'm not missing any oil I'm going to try to flush the rad and see if it gets dirty again.

This chain rattle at start up, is it loud? 

Yes, if the chain tensioner isn't pumped up, you can hear it over all the other engine sounds for a second or two.  Longer if they are in poor shape.  If they are still rattling after a minute or longer.... there is your sign.

Pulled the rad, repaired the bad core with some marine JB weld.  Letting it sit overnight.  Antifreeze full of crud, like the stop leak crap.  I was hoping since I knew the guy i bought it from he'd be a little more honest.   Never trust anybody trying to sell you something, eh?

While I had the tranny cooler hoses off i did a tranny flush.  Wow.  Like trying drain dark cherry jello.  Tomorrow topping the rad off, going for a 130 mile trip and seeing what's with the antifreeze.  Kinda hoping I don't have to do the head gasket but I'm almost committed to doing it anyways.

The power steering fluid is getting low but I don't see a leak.  And there are drops of oil on top of the diff I can't explain.  I'll need to go get an under car was to get rid of the dirt road buildup then off to look for oil

Release the steering rack boots - see if there is fluid trapped in them - there often is, but there should not be.  Seepage past the seals in the rack accumulates in the boots.

100 miles on new coolant, so far clean.  Changed the oil because old one was thick.  Now I hear the chain rattle.   I don't now if I should do the head gasket since I'm already getting into the timing chain...

Keeps throwing a p1408.   Steam cleaned the engine, 1.5 quarts of water over 15 minutes.  Will know if it cleaned it or not.  Where is the PVC valve, the thin purple valve at top of valve cover?

Why the constant focus on the head gasket - are there any symptoms of a failed/failing head gasket?

Timing chain rattles are not unusual on engines that have been neglected, however, before tearing into the engine, make sure that the rattle is not coming from the accessory pulleys on the front of the engine - remove both belts and start the engine, you can run it for a few minutes without them.

If it's a short 2~3 second rattle, make sure you're using an oil filter with an anti-drain back valve, my preference is the OEM Suzuki filters.

The PCV valve is on the right side of the valve cover, half way down, with a short piece of hose to the intake.

Fordem is correct, and yes, you might get tired of hearing that, but he is generally spot-on with his advice. 

I wouldn't consider pulling the head unless you had a specific reason to.  I haven't heard any of the symptoms you have described so far point to a head problem.  Sounds to me like the radiator needs replaced from your descriptions.  Even if you stop the leaking.... if it had that much stop leak in it I've got to wonder how well it is cooling your engine.  Excessive heat (or lack of ability to remove heat) will cause problems and repairs to the head.

Sea Foam works to clean-up excessive varnish build up in the engine, the oil pick-up screen and oil pan.  I began to have a little too much timing chain noise developing in my truck.  I added about 2 ounces (no more) of Sea Foam into my engine during a new oil and new filter change.  Ran it for about 3K miles, then changed the oil and filter again.  The Sea Foam removes varnish and built-up crap inside the block AND it cleaned the timing chain and tensioner as well. My timing chain noise became "normal" again... as in some times you hear it at start up and some times you don't.

N.A.P.A. branded filters are very good filters as well.  I think they are re-branded Wicks filters.

Focusing on head gasket was caused by the oily creamy coolant.

Carquest filter with anti drain back.   10w30 Castro gtx.   I did use half bottle a foam 1 hour  before oil change.  Big fan.  Make my own.  1/3 odorless mineral spirit and 2/3 kerosene or diesel.  5 percent alcohol, I usually don't worry about it.