mostmatt

Hi all,

First post, longtime lurker. My question is as follows:

I have a 95 pickup, 22re 5spd with ~205,000 miles. Bought the truck with 160,000. P.O. replaced the water pump, timing chain and chain tensioner/guides at some point. I've only replaced the alternator, adjusted the valves a couple of times, and done the plugs/plug cables/exhaust manifold gasket. Everything else is untouched as far as I know.

After shutting off the truck after a short drive the other night, I heard coolant boiling in the radiator and saw a bit of steam coming out from under the hood (from the reservoir overflow tube). I immediately turned the ignition to acc and checked the temperature gauge. It was a tiny bit below half way, right where it always is.

I searched the forums and saw a few people mention that a HG leak can cause boiling of coolant because the system doesn't pressurize. I've been aware of a very slow leak from the cold water rad hose for awhile, so I thought that could be it. Hoping this was the cause, I fixed the leak, and haven't noticed the boiling since.

However, after reading about HG issues, I became suspicious and started checking some things out. I warmed up the truck with the rad cap off and saw air bubbles coming up into the rad. Then I got a NAPA block test kit which tested positive for combustion gasses in the rad. I also noticed that if I idle the truck for a while, water drips out of the tailpipe and makes a wet spot on the ground, even if the truck has only been sitting for a couple of hours since the last drive. It's very dry here (CO) so this doesn't seem right. I don't see any oil in the coolant or coolant in the oil.

Now I'm 95% sure I have a blown HG. My real question is, why did this happen? I'm extremely diligent about watching the temp gauge and checking the coolant level. The coolant has never gotten more than a cup or two low (due to what I always assumed was the leaky hose), and I'm almost positive it's never overheated (according to the dash gauge) since I've owned it. The temperature gauge never moves from just below half way. It runs and drives just like it did when I bought it (I can usually hit 80 on the highway if it's really flat).

Money and time are tight, so I'm going to do the HG myself. It's my DD and once I take it apart, I need to get it done within a couple of days at most. My plan is to get the head machined / checked for cracks by a local shop (already talked to them), and to put in an OEM gasket. If the head is too bad, I'll replace it. But I'm worried about not knowing the root cause of the HG failure.

What I'm really wondering is,

1. Do headgaskets ever just go bad on their own? Is it possible to have a HG blow without ever overheating the engine?

2. Is it possible that the engine could overheat and the gauge continue to read normal? Ever since I bought the truck, I've occasionally heard air bubbles swirling around in the heater core when the heats on and I rev the engine. Also, I drained the cooling system when I replaced the alternator (20k ago), and I may not have gotten all of the air out on refill. Could this cause the temp gauge to read normal when the engine is actually hot enough to warp the head?

3. Is it possible that the HG has been blown for the last 40,000 miles? It always runs cool, and I've never seen mixing of oil and coolant in all of the oil changes I've done. I've also never noticed steam from the exhaust after it's warmed up (still don't).

4. If I check the oil for coolant everyday, can I continue to drive it?

It's going to be rough getting it done fast, and I'm afraid I will get it back together without the root cause being addressed.

I apologize for the long post, but I wanted to include everything. Many thanks in advance for the help.

Terrys87

iTrader: (1)

I had one that a head bolt had somehow loosened and let it blow the gasket. I bought the truck used so may the PO had replaced the gasket before I got it, not sure what the history of it was.

I really dont know for sure, but one thing I suspect that cause a head gasket to blow is the head is aluminum and the block is cast. They are going to heat and cool at two different speeds as the metal expands or contract.

Poor maintenace on the cooling system as the fluid gets old and causes corrosion in the head, I have seen that. Just my 2 cents.

RAD4Runner

Try this.

While engine is cold, before The very first time you start it in the morning, take radiator cap off. Start engine. You should not see bubbles in radiator. If you do, that's combustion pressurizing the cooling system through bad HG. Saw it when my 1986 with 22RE blew its HG. Saw it on our Honda Civic, Saw it today on another's MoreFunner with 22RE.

This scenario may not necessarily give you milkshake coolant because it's the the combustion gases that goes to the cooling system.

Your temp gauge may not show an overheat either.
This is my opinion... Could be because coolant boils at lower temp because the leak causes less pressure anymore, or coolant's too low, it does not touch the temp sender. I saw this happen the day before I found my bad HG. I was driving in 3-digit temp in San Bernardino County, CA and noticed that temp gauge showed unusually low temp. I thought it may have been because I was running on the freeway. I made it to the trailhead without incident. Upon leaving the trailhead 2 days later,engine overheated and I saw thr symptoms above...

wyoming9

iTrader: (1)

Since it seems your not really losing coolant don`t appear to be getting the white crop duster smoke.

You can try a compression check if the cylinders are all close

Pressure test the system see if it holds pressure.

Try these two tests it will give you a better idea!!!!

Really coolant in a engine seems to pick up hydro carbons the minute you put it in

A bad radiator cap will cause some of your same issues.

The fluid you see on the ground does it have the smell and feel of antifreeze you always get condensation hot exhaust cooler air temps no matter how dry the air.

Now if it was time to do the timing chain again I would say go for it.

Yes it is possible to have a head gasket fail with out a major over heat just the continued thermal cycling between the different metals can cause a failure.

These engines can be a real pain for getting all the air out of the cooling system I put a tee in the heater hose with the cap off as I fill the coolant sees to make it lots easier.

When ever these type of jobs have a dead line and your under pressure things go wrong.

If you have talked yourself into thinking you have a failed head gasket your not going to be satisfied till you change it.****

remember head bolts get torqued to 65 foot pounds !!

Badger62811

Mine failed the same way. Once I got the head off it was clear the HG failed between a coolant port and exhaust port allowing exhaust to enter the coolant. The only way I knew I had a problem- went to McDonald's for some food kinda late at night. It was cold and snowing and when I went to order my idle started surging so I turned the engine off. Heard a weird noise but didn't think anything of it. Started truck back up, got food, headed home. 10 min drive home and my heater started blowing cold. Got home with an iced over windshield turned her off and steam blew from the radiator cap.

HG fix isn't too bad, I'm getting ready to do it on my new truck because guess what- same symptoms. Just use new head bolts, and re torque them after 50 miles.

mostmatt

Thanks for the replies! I started the truck this morning with the rad cap off and there were tons of bubbles coming up right away. After my commute to work when the motor was hot I pulled the plugs and did a compression check. Got between 150-155psi on all 4. Weird, I was expecting to see one or two really low. Maybe there is no leak after all?

RJR

You might try a leakdown test. The standard compression test isn't particularly sensitive, especially to small leaks. A leakdown test injects a controlled amount of air into the cylinder and allows you to listen and observe where it's leaking out. Even a near-pinhole leak will show up if the test is done properly.

mct75

You can also try stretching a balloon over the radiator fill port and see if inflates.