I read your whole thread and although I'm pretty sure it's your head gasket (main things that popped out at me are the smoke coming out and the "in-explainable" loss of pressure). But I really, I mean really, like your diligence in trying to figure it out yourself. When I was younger, that's exactly how I started , and since I've learned to rebuild motors myself.

So I have one more thing to try for you...put some UV dye into the coolant and then do the coolant pressure check again (with the tool, pull the spark plugs before). Make sure you run the truck for a while after adding the dye and allow it to heat up, to give the dye a chance to mix in. Then, once the pressure has decreased (meaning the coolant has leaked SOMEWHERE) use a cheap shop light (or any light with a bulb socket) with a UV bulb in it to check where the coolant went. Because your spark plugs will be out, you should be able to shine your UV light into the cylinder and if there's a leak there you will now know. If there's a leak somewhere else, you will also know. Either way you're gonna get something out of this because you probably want to find out where the leak is .

A few other things:
- I don't think it's your water pump because you're able to do the burping procedure. A bad water pump would allow no movement of coolant at all, therefore you wouldn't really be able to get the water out.
- I don't think it's your thermostat, because you've replaced it twice and checked on it once more (some would say that's a bad assumption...but come on now)
- I don't think it's your cap, because a non-pressurized system on that truck shouldn't boil over unless there's another point of failure.
- A cool lower radiator hose can be an indicator of a head gasket issue.

Good Luck!

EDIT: My guess is you're going to find a coolant leak into the #6 cylinder through the head gasket, because that's where the stock exhaust manifolds concentrate all the heat.

EDIT 2: Whatever the problem is, think about trying to fix it yourself. Yes, even the head gasket. You seem somewhat comfortable under the hood and from your posts you seem like you pay enough attention to detail. Remember, all you do is remove parts and remember what you did and do the same thing in reverse order and you're set. There's plenty of information on this forum, in a Hilton manual and other places online to answer any questions you might have if you get stuck. Just an idea to save money!

avg compression 187.1. Isn't bad, not excessivly high or low (IMO). It does have maybe some excessive carbon build up(#3 cyl@200psi), and less than stellar rings(#2, 185 dry vs 225psi wet). #6 is the hottest cylinder this would account for the compression, it's likely the cleanist also for the same reason.

Aside from the imbalanced readings it seems ok, but that's just one opinion and you'll have to decide for yourselves if you're comfortable with it. The gurgling is gone the temp is relatively stable.

I'd still maybe consider the fan clutch, there are some threads here about refurbishing one (drain clean and refill), if this is less than perfect it would cause you to run a little hotter all the time but bring it back near what you're used to idling.

You may also want to consider the pressure imbalances, there are threads on seafoam and water injection, both of these will remove deposits. Beware they might damage the oxygen sensor, plug up the cat, and they'll definately make the neighbors think you just blew up your engine or caught something on fire. My advice if you want togo this route is pick up an extra set of exhaust nuts from the dealer(they're tapered and one time use items), disconnect the exhaust at the down pipe(junction before o2 and cat) and let it spit the gunk all over the parking lot.

And since it's a 3.0, you might want to add engine savings fund to your list. If she likes it now she'll love it even more with a supercharged 5vz, she might eventake you wheeling

It's brand new. What do you think about an inline filter? Maybe it's got some RTv or other gasket materials running thru it.

How about a good flush, keep in mind he's in an apartment/condo and not supposed to be making a mess

They found the water leak in a hose finally. (Don't forget to replace that, if it's in the hose and not a connector it could give out while driving, if it is in a connection it may give out or may decide to reseal it's self)

If it's not pressurrized it will boil sooner no pressure means it boils off at the same temp water on the stove instead of 220-260 (or whatever it is)

A cool hose just means the radiator is doing it's job as long as it's flowing, ignoring things like the thermostat not opening and the pump not circulating. But of course I don't mind being wrong so long as some one educates me How does a cool hose indicate a head gasket failure exactly?

She has a manual, If you're stuck in a Hilton I don't think any books going to help much but maybe I should find one just in case.

I'd try the fan clutch.

You're right about it boiling sooner without pressurization, but in a well functioning cooling system you should never reach atmospheric boiling temperature to begin with. This is sometimes invalid in newer cars which are designed to run way hotter.

You're also right about a "cooler" hose being normal. But a "cold" hose is definitely not. The bottom hose should always be warm, as the cooling system cannot cool the coolant, rather it just makes it less hot, if that makes sense. This is where having experience in "how hot is normal" helps.

Hilton manuals are not the best thing out there, by a long shot. I always reach for a factory manual if the information I'm looking for is important enough. But, for a novice DIY mechanic, it's a very useful source of information as it's easily understandable and lists things seasoned mechanics would never need repeated.

Lastly as to why a head gasket failure would cause a cool bottom hose...that's a tricky question. Different head gasket failures can cause different symptoms. For example, on the supercharged 4Runner I used to own, I managed to crack my heads in 4 different cylinders, yet the car never overheated and it only leaked coolant when it was off so that I would have a hard time starting it in the morning.

Other scenarios aside, the main reason head gasket issues usually cause overheating is because they introduce air into the system, by forcing combustion gases into the cooling system. Then, once the air is introduced it has the same effect as a system that's not bled properly...coolant doesn't circulate properly and the system can't cool efficiently. This is another reason I think it's the head gasket, because the OP mentioned that he tried to get the air out multiple times and the problem comes back after a mild period where it seems to get better.

One more thing...I'm not sure if this was mentioned/checked. What's the oil look like? Is it milky at all?

It dose't sound like a blown head gasket. It sounds more like a clog in the cylinder heads. I have seen the coolant holes in head gaskets clog up from the radiator fluid not being changed in the proper intervals. The metal in the head gasket corrodes and blacks or restricts the coolant flow through the head causing minor overheating. Or if a previous owner ever used stop leak it will also clog up the heads.

Hey fellas, Sorry I've been MIA, I'll catch up on the recent posts. Thank you all very much for taking the time to offer up the advice; I've skimmed but need to go back through.

Was considering the "chasing a ghost" theory over the past few days and considering the next steps if any to try to resolve the slightly higher then normal temp. Got the call from wifey today, it was exceptionally nice, sunny, and high was almost 80. Wifey had on the AC and although the temp gauge didn't go any higher then before it did the boil over into the reserve routine... ouch.

I've got the cheepo fan clutch half way in, I want to replace the bolts that put it back onto the pulley because they are verging on stripped, prolly mostly my fault but may have been a bit ate up before I got started and every place is closed now. I didn't do a great job getting behind the blade but think I could do a better job next time. I also broke the fan shroud. I suck, but I'm learning and getting better. The fan shroud cracked at one of the thinner spots on the passenger side of it, going to try out the fan clutch with the shroud off but will get a replacement shroud on there.

Not sure if this is a symptom... Has happened a few times and just needs the right circumstances to reproduce, I think it is an unrelated issue though. If driven to elevated / heated all the way up temp. Then shut off for about 10 minutes where it starts to cool but not much yet, temp slightly below normal, and then you start it. It won't be able to stay idling without giving it some gas. Runs rough and either wants to cut off or cuts off without gas. After driving a minute or two it's always been fine at the first stop light. My buddy thinks we should check the timing on that and is going to show me how on Thursday; he's got the gear.

If the coolant system tunnels in the engine or gasket are clogged will a flush take care of that or would it need to be pulled apart?

My current ideas are see what this fan clutch does, consider a full coolant system flush, try to investigate the water pump (I never did that test on the heater hose to see how the flow is). Im not seeing much point in another "block test/combustion leak test" because you all seam to think its not the head gasket.

My buddy helping me with the timing system and who helped with the compression tests who is not a mechanic, but does all his own stuff and is a very clever cat, does not think a coolant system flush is a good idea. He's thinking it could cause problems with seals and that goop I get out may just be what's holding that stuff together. I could put the old radiator in for the flush and put the new one back in after (or can you flush everything but the radiator?). What do you all think on the coolant system flush (and eric the car guy's heater core flush with reverse air flush)?

Flush might just lodge the gunk somewhere else, creating back pressure which then breaks questionable hoses, ect. Which is what your freind was getting at.

Definatly flush w/o the radiator hooked up, it's brand new and you don't want that crap going into it.

Here are a few pictures of clogged gaskets, to give you an idea of what you are up against.

http://img.photobucket.com/albums/v1...7/100_0853.jpg
https://www.yotatech.com/attachments...t-gasket-2.png

Of course these are 22r-series gaskets so yours are a little bit different

http://i173.photobucket.com/albums/w...A/P5010008.jpg
should look closer to this
http://www.n7uic.com/pictures/fel-pro1.jpg

Co_94_PU, you've been so helpful through this process, thank you.

So I see the clogged up gaskets, but what's the resolution if that is the problem? New gasket, flush, other?

Do you also think flushing is a bad idea. OR are you waiting on fan clutch results to pass judgement? Has head gasket been ruled out or is it "not badly blown/leaking" or "likely not the gasket"?

if its not drinking/burning coolant, and none showing up in the oil pan. It's not currently leaking/blown. That doesn't rule out that it has failed and pluged it's self up, but I'm never that lucky if I was I'd play the lottery, when they blow on me they rapidly start making milk shake in the oil pan and knocking and blowing smoke out the exhaust.

Flushing will definately get something out, wether thats from the walls of the water passages or from the gasket there really isn't any way to know. As long as you keep the water pressure within reason, say the 15# or so the system is designed for, it can't hurt anything.

Probably a good idea to not flush the engine into the heater core, since you know it'll drop the engine temp, you don't wanna plug that up it might save your engine long enough to get it home and parked should the nead arise So tie those two hoses together with the flush T, disconnect the radiator, remove your thermostat, and proceed to make a mess all over your parking lot If you want.

When you refill the system use premixed antifreeze, or pick up some distilled water (Not that bottled mineral water junk distilled!).

Not sure I should mention them since I don't have any recent first hand knowledge but I guess I will. There are various companys that make flushing fluids. Thoro Flush is one, this is essentially a water softener(sodium carbonate) or a water softener and sodium phosphate(TSP?, dry phosphoric acid) depending on the manufacture date or msds you look at.

Sorry missed a direct question. Blocked passages lead to hot spots, hot spots lead to gasket failure or a cracked block (Usually the former).

Ye' waiting for the clutch results, that'll be the optimal outcome. Granted head gaskets don't cost much(if any) more than that but once your in that far you might aswell do the whole timing belt and tensioner too, and oil&filter and coolant change, and head bolt set, and maybe some others I'm over looking like the cover gaskets. And you neighbors are definatly going to notice when you start putting big pieces of the engine in the back of the truck

The bolts I rounded off are coming from warehouse, will be in tomorrow so hopefully I will have fan clutch news tomorrow night.

The fan shroud I cracked is 100 at the dealer, any cheep alternatives? JBWeld and a splint? Maybe hit the junkyard? I'm planning on testing the new fan clutch with it off, I know it directs the air some but I'm thinking not enough to invalidate the test????

I think we are pretty set on dropping in a crate engine if it comes down to head gasket. 1500 to do the gasket fairly decent with a top end quasi rebuild and replacing the right stuff. 3K installed is what we were looking at for the crate with MLS gasket, good studs, from a reputable machine shop that should get the job done right. I tell her you don't put 3k into a vehicle that's worth 3k after the work; I lost that argument. The truck is in really good shape cosmetically. Couple minor body issues but good, and inside very good for 20 years old.

i pulled apart a 1990 dodge 318 engine a few months back. most the water ports where the head meets the block were clogged. i pressure washed the crap out of the ports in the block to try to clean some of that crap out. that dislodged some stuff but not all of it. i highly doubt a coolant flush would remove any clogs you have.

i say do head gasket repair. you're obviously showing good results with the compression test which means your bottom end is still good. might as well just do the head gasket replacement because it'll happen sooner or later, especially since you are having over heating issues. the last thing you need is is to blow the head gasket the rest of the way and completely destroy the aluminum heads with over heating or destroying lower end with milky oil. probably cost you less than 300 bucks if you do it yourself. there are probably more head gasket replacement threads on the 3.0 engine that there is on any other engine out there. so you'll have tons of references to do it yourself

^^ what he said DIY it, for that 3k you can buy another 4runner and do the HG job twice and you two will have matching gas guzzlers I might up the cost estimate to 500, not sure if he factored in tools and consumables. Still very reasonable, and plenty of walk-thru and howtos. And the bit about someone noticing was mostly a joke, but sure if you look you can find someone to loan you some driveway space.

right....... i was thinking 300 just for the parts. go to rockauto.com and check out head gasket kits. it'll have everything you need to do it. i also didnt count in machine work. while you have the heads off, get them them reworked by a machine shop. probably cost you another 150, 200 or so. they should clean them, resurface the valve seats, install new valve seals, and plane them flat if they are warped. should also include inspection for cracks.

Quick status post then try to get more done.
The new fan clutch does not resolve the issue (but the fan shroud is still off, it that enough air redirection to matter?). Let it idle up to normal temp and started driving 35-45mph temp knob on cool but AC off and not blowing any air. The temp gauge did move up to that slightly elevated point once driving for a couple min. Stop to pick up JBWeld to patch up the fan shroud; no boiling over into reserve. Crank the AC on drive about 20 min, AC not blowing cold, never got the AC fan to come on. When we stopped it was not boiling over into reserve but I am pretty certain it was boiling in the upper radiator hose and believe if we drove it harder, longer, or it was a bit hotter it would boil over.

Would need more testing but I think it would not boil over with the AC off but pushed to cold, pushing to hot is probably better but we hit the mid 80s today, pushing to hot with fan prolly best, and if I put the AC on I think it would boil over.

I'm going to see if I can get the engine codes with the paper clip. Then try to patch up that fan shroud and search craigslist for one. Considering flush (flush heater core separate from the rest of the system, can I get the radiator out of the flush loop too?), better water pump testing, and engine rebuild. Looking at setting a two week deadline to pulling the trigger on rebuild. That's really not something I can DIY at this stage. I've learned allot but I'm not there yet, don't have the skills, don't have the tools, don't have the time, and need it up and running hence the deadline. It's a daily driver.

Sincerely,
Sad man with sad wife in VaBeach

Don't quote me on this, but yes the fan shroud would make a large difference. The air would be blowing every which way, but with the shroud it directs it at the block.

Thanks for the input, about to JBWeld that thing back together with a couple splints and will get it on tomorrow evening. Even if that's not the problem I appreciate you saying that because if I pull that new fan clutch without trying it with the shroud on it would always be in the back of my head.

Will definitely give it a shot with the shroud on.