hirsche23

So my 89 t4r -22re heats up on me the other day-had the top off and used the heater on my AM commute(20 miles) upon getting close to work it just about overheats on me,I fill it with water before heading home,it was good,replaced the t-stat when i got home had the exact same problem today! So after searching and reading many posts I have come to these conclusions: 1.I need a bypass t-stat accordding to 4crawler or 2.my head gasket is toast, or 3.i need a new rad cap. I have only had this rig for 1500 km and the guy I got it from said they replaced the head gasket recently,And that the engine was rebuilt. I don't know if they cleaned or had the rad checked. Now, when I get it warm the idle is rough and it blows white/light gray smoke at idle. This unit drives and runs great other than this problem with no power loss that I can tell. It doesn't blow white smoke all the time-only when it is warm and sitting at idle for a minute or 2. Where should I start guys? Any suggestions-obviously I'll do the cheaper ones first,but if it is the HG how do I know that it is bad?

Asha'man

If your headgasket is blown, you can check your oil and it'll look like a chocolate milkshake. It would probably be blowing white smoke all the time if that were the case, though.

Brian

8422r4Runner

Radaitor's and heater cores can both cause a restriction in water flow. A easy way to test is after the rig is warmed up. Pop the hood and feel both radaitor hoses and both heater core hoses. All should be about the same temp.

One way cooler than the other would point to a restriction.

ovrrdrive

I'd start with a copression test. That will tell you about the HG and about the condition of the rings.

If that's fine, do the pressure cap. It's cheap and when they get weak they do indeed cause an engine to overheat.

There's no reason to bypass the thermostat. It's part of the cooling system and when it works properly it actually makes the engine run cooler with it than without. The system is designed to run with it and it's not a good idea to bypass it.

My money is on the HG. as the problem. White/grey smoke is usually water vapor, which would be consistent with a blown HG. Do the compression test.

As far as how bad of a job it is, well it's not too bad but it is tedious and takes a non-mechanic a long time to do. I just had a plastic timing rail break and go through th bottom gear on my truck which jumped the time, and gave me 4 bent intake valves. I am within an hour finally of getting it back together and I'll tell you this has been one hell of a job.

I bet I have 20-30 hours in it total. But I also have saved about $1500 in labor by doing it myself. There's lots of good info out there to help including the factory service manual online if you decide to do it yourself. It's definitely do-able.

The worst parts of it for me have been loosing/mis-placing bolts, mixing bolts up so I don't know what bolt came out of what hole, and my labling system of the vacuum lines went to ÅÅÅÅ and I have a bit of a mess now. It really pays to be very meticulous when you take everything apart. It not only saves time but it will make the difference between a good job and a nightmare.

SlightlyModified

Yes a cap can cause it. For every 1psi of preasure will raise the boiling point I believe 3 degrees F. If you have a faulty cap, it will lose preasure. I would do a cooling system Flush. and replace the cap. As suggested check your oil, if it's milky, a sure sign of HG issues.

ZUK

iTrader: (1)

This test will give you more info as to a HG issue or a clogged radiator......

With the truck relatively cool, use a towel and safely remove the radiator cap. With the level about halfway between the fins and the top, start the engine and watch it for 10 minutes. Monitor the temp gauge for hot temps.
After about 5 minutes you should see a small flow of water from left to right. It will start and stop occasionally(flow). Ater it gets up to temp, you should get a constant left/right flow and increasing rpm will give a faster flow. Look for "suds" in the water(foamy)..........also, does increasing engine rpm want to cause the rad to overflow?

My 87 Runner with 3 core had a blown HG and the rad did suds.....it was caused by over-heating from a clogged rad and if yours is clogged, the left/right flow will not be swift and may overflow when the gas is applied.

4Hummer

Do you go mudding in your Rig ? You sure the Rad isn't filled with Mud not allowing air to flow threw it ?

Ask me how I know.

hirsche23

good ideas guys,i will do the comp test and rad cap.on the HG thing, if the HG was bad or leaking would I see white smoke from the exhaust all the time? Also my oil looks fine.when it does get hot the rad fluid is way down -does the water boil away and leave just the glycol?

TNRabbit

I had a similar problem and it was the water pump slowly leaking antifreeze. Check the weep holes in the timing belt covers (lower) for water/antifreeze.

hirsche23

I went out and looked under the oil cap and found the sludge everyone talks about it looks like this.

So now I am starting to really consider that a bad HG may be the problem as it does not leak a drop of coolant- it just dissapears.

4Hummer

a little bit of sludge is normal on the oil cap this is due to condensation buildup.


however MILKSHAKE oil is very bad. hows the rad ?

hirsche23

the oil is fine I don't know about the rad,i did a test today that a buddy told me to do. I started it up and went to pop the rad cap off to see if it bubbled, well it shot out like it was under a ton of pressure this was after idling for about 15 sec from being stone cold.the cooling system shoud not produce all that air right?Is this because i am getting pressure in the cooling system from the cylinder?

mr toytech

if it is blowing out of the rad. that soon u prob. have a blown hg. or a cracked head.

eightyfive

very common mistake people do is overfill the overflow bottle and wonder where the water goes when its half way after 10 miles of driving...the overflow bottle is supposed to be halfway! anyway, to check if its a tstat problem run the engine to operating temp then feel the upper radiator hose, it should be hard or filled with pressure. the top hose and radiator is always hotter than the lower. to simply test the tstat, you take it out and boil it in a pot...if it opens it works.

my engine was running hot until i went 3 core...

but i think that you think your losing colant but your just really overfilling the overflow bottle...am i right? very common mistake.

if tstat works and your still running hot, you could have a restricted radiator...clean it or flush out your cooling system.

rdharper

Right... compression test, or leakdown test. Wouldn't drive it until you fixed this, as if it is the HG, you can quickly double the cost of repair.