Question for the engine gurus

[W1RKW]

I have a 1999 Mazda B4000 with 4.0l engine.  It's basically a Ford Ranger XLT.

My temp gauge has been pegging for about 10 seconds then falling to normal operating temp after startup and staying there until then next startup after getting down to ambient temp.  I discovered that the coolant level was low yet the recovery tank was half full so I replace the radiator cap figuring it wasn't pulling a vacuum to draw coolant when cooling down and topped off the radiator. That didn't work.  Recovery tank has overflowed now and is still full to the top even though the engine is cold. I haven't pulled the cap to check the radiator level but suspect it will be low again.  I still have an issue with the gauge pegging but not as often. I was going to replace the thermostat but now I'm thinking I have an issue with a head gasket or intake manifold gasket which these engines are famous for.  This all started recently and I have never had evidence that the engine was consuming coolant or leaking it out to the ground.  It has a 140,000miles and the water pump is original.

Anyone have any idea what I'm dealing with? Thanks.

[KE5YTV]

Bob, I've had the same thing happen on a Ford 289. Blown head gasket. 

Mike

[W2PFY]

I have had blown head gasket before and one of the signs is air bubbles in the coolant when the engine is running along with high coolant pressure without the engine being hot. The other bad sign is when your oil turns a milky white. That means there coolant getting into the oil.

It sounds to me that a head gasket could be blown.

[Bill, KD0HG]

I agree with the head gasket diagnosis.

Now...There is a sealer product I used several years ago. Bought at an auto parts store. The deal is that you need to completely drain and flush the cooling system until there's nothing but straight water in there. This sealer is incompatible with antifreeze while it sets up.

You remove the thermostat.

You add this sealer to the cooling system and top it off.

Flush it again later and fill up with yer favorite antifreeze solution again.

This sealer worked great for me on a diesel tractor with a blown head gasket. Loosing coolant during combustion. Been almost four years now.

But I don't remember the name of the sealant...

[WA1GFZ]

You could have a cracked head and high pressure air is leaking into the water but water isn't leaking the other way...yet. Could be just a gasket.

[W2VW]

Have someone with an exhaust gas analyzer sniff the radiator for hydrocarbons with the engine running.

[WA2IXP]

When you have a small combustion gas leak into the cooling system it often shows up like your problem. Exhaust gas creats an "air" pocket around t-stat delaying the opening until the engine gets real hot. When everything is up to temp and coolant is circulating it still works fairly well. Often the heater stops working from gas trapped in it as it is a high point in the system. Check with exhaust analizer (w2vw). Another way it to put the overflow tube from the rad into water with the cap removed. Cover the cap opening with rubber so any pressure will bubble up in the water. You'll see some bubbles at first but a bad gasket will give a steady stream. After it gets worse you won't need any of these tests to tell. With the cap off the cooolant will gush out as soon as the engine is started. Jay-

[KC4VWU]

Yup, everyone's pretty much nailed it. A small combustion to water jacket leak will produce tiny bubbles that will pop and release little plumes of smoke (exhaust gases) while the engine is running. If you remove the radiator cap and take a whiff, you'll probably notice a nasty, acrid odor. Symptoms will vary depending on make and severity. I've seen the Cadillac Northstars range from billowing out a constant smokescreen to actually pouring raw coolant from the tailpipes. Good luck!

73, Phil
  

[The Slab Bacon]

If you have a blown head gasket, it will constantly blow water out. With the engine at operating temp, and the pressure RELEASED remove the cap. If it is pushing water out you have a head / head gasket problem. Also stick your nose in the radiator and take a really good sniff. If it smells like exhaust and/or raw gas, you have a combustion (head gasket) leak. If it doesnt, try replacing the thermostat. they are cheap and will, on occasion, go bad. I replace mine every 50-60K (along with the belts and hoses) whether it needs it or not, just as an insurance policy.

If you do NOT have any combustion products in the coolant, your problem sounds more like a bad thermostat.

[W1UJR]

Hi Bob,

Generally if you have a defective cylinder head gasket, or coolant leakage into the combustion chamber, you will experience some degree of coolant loss, and smoke from the exhaust. I've seen several cylinder heads where porosity occurred, allowing the coolant to seep into the combustion chamber, creating a smoking on start up. If you suspect coolant leakage into the engine, inspect the spark plugs, one or more will be very clean looking on the cylinder affected, the coolant acts as a steam cleaner on the plugs.

If it were me, I'd shotgun in a temp sensor and thermostat and retest. Also be certain that air pockets are removed from the cooling system, we use a vacuum bleeding process here, in your case, fill up the upper hose with coolant before you start the engine, leave the cap off the coolant tank, and run the heater at high temp to bleed out the air.

The cost to try the t-stat and sensor is cheap, and if the problem remains, then you can check for a combustion chamber leak. A number of companies sell a test dye you can use to determine if combustion gases are present in our cooling system, see your local auto parts dealer.

See the attached TSB.

[WA1GFZ]

cooling system sealer goes directly into the heater core plugging it nicely.

[W7SOE]

I was a BMW mechanic for ~13 years in a previous life.

The way we would test for blown head gasket or a cracked head was:

Pull the spark plugs

fill the coolant reservoir all the way to the top
screw in an air hose into the spark plug hole with a normal air line fitting on the other end.  (compression check type hose)
put that cylinder at TDC
slowly connect the air hose to line pressure (The cylinder will have to be exactly at TDC or it will kick over and you will have to try again)
Watch the coolant level, even the smallest problem will be indicated by a rise in the coolant level.
Repeat for all cylinders.

We did this for all pre-purchase inspections.

Of course not everybody is equipped for this at home.

73

Rich

[W1RKW]

OK, Here's the latest troubleshooting steps I did.  I left from work and pulled the rad cap.  Started the engine and put my hand over the rad opening.  No bubbles in the recovery tank. Maybe there's some hope.  Don't know if I didn't hold it long enough but held it there for a minute. Put the cap back on and drove off.  Temp gauge pegs briefly all is normal after that. Get home and turn off engine.

I'm going to try  a new thermostat as soon as the engine cools down.  Since thermostats are closed when cold I'm guessing its sticking closed until it gets real hot then pops open as suggested by a previous poster.  And because it is sticking it's causing coolant to boil and push out.  

The thing that bothers me though, I had the coolant flushed about 2 months ago and there was no sign of a  problem after the maintainance.  The recovery tank level never changed.  I'm thinking I may still have a gasket problem and coolant is slowly being consumed or the person who changed the coolant didn't refill 100% but that doesn't explain why when I added coolant that it was pushed to the tank so maybe I have been driving for the last 2 months on a low cooling system.

I'll know better in an hour or so.

Everyone, thanks for the tips and service bulletin.  Great info!

Stand by for more info.
B

[W1UJR]

Since thermostats are closed when cold I'm guessing its sticking closed until it gets real hot then pops open as suggested by a previous poster.  And because it is sticking it's causing coolant to boil and push out.  

Nailed it!
Occam's Razor - I teach all my techs that.

Or you could bring it in here...I hear they do good work!  



http://atlanticmotorcar.com/ams_photobook.htm

[W1RKW]

I could bring it there but it's a 4 hour drive.    Though, it would be a good excuse to visit a well equipped ham shack!

New thermostat shows promise.  Took the ole beast for the test drive and temp is stable.  Old thermostat does indeed stick in comparison to the new.  The big acid test will be a drive from dead cold.  Also monitored the radiator opening while refilling with engine running no bubbles. Whew!

I'll know better tomorrow but I think I am good.  Also think the person who changed my coolant didn't refill to capacity. 

Since thermostats are closed when cold I'm guessing its sticking closed until it gets real hot then pops open as suggested by a previous poster.  And because it is sticking it's causing coolant to boil and push out.  

Nailed it!
Occam's Razor - I teach all my techs that.

Or you could bring it in here...I hear they do good work!  



http://atlanticmotorcar.com/ams_photobook.htm

[WB3JOK]

I hope it's the thermostat - if the old one, now in your hand, is "sticky" and the new one isn't, that's a good sign 

However... my '81 BMW 745i (factory turbo with increased boost) ran for over a year and thousands of miles before I finally got tired of it instantly overheating and puking out all the coolant every time I ran into boost. Under light throttle/cruise it would run summer, winter, no bubbles, no coolant loss, no coolant in the oil and vice versa. But hit the turbo just once and I'd be on the shoulder within 30 seconds waiting for it to cool down so I could put in some more $10/gal antifreeze 

Last spring I got around to changing it. As soon as the head came off, it was pretty obvious which cylinder had the problem 

[The Slab Bacon]

I could bring it there but it's a 4 hour drive.    Though, it would be a good excuse to visit a well equipped ham shack!

New thermostat shows promise.  Took the ole beast for the test drive and temp is stable.  Old thermostat does indeed stick in comparison to the new.  The big acid test will be a drive from dead cold.  Also monitored the radiator opening while refilling with engine running no bubbles. Whew!

I'll know better tomorrow but I think I am good.  Also think the person who changed my coolant didn't refill to capacity. 

A simple test for the old thermostat:

toss it into a pot of water and put it on the stove with a thermometer in the pot also. When you see it start to open pull the thermometer and check the temp. It should be somewhere close to temperature stamped on the bottom of the copper "pellet". If it is way higher, you know it's toast.

[WA1GFZ]

I had a t stat stick once on a real cold morning. Sounds a lot like your finding. Water in the heads gets real hot and boils until the stat opens. You will have a lot of heat for a short time

[W1RKW]

It was definitely a sticky thermostat.  Started it up this morning.  It was 0 degrees.  A good test.  Temp came up normally and held steady where the needle always rests when warmed up.  No coolant escape. Recovery tank level is normal.  It's a relief that it wasn't more serious.  Thanks for everyone's help and advice.  AMFone has a great knowledge base.

[W2PFY]

inspect the spark plugs, one or more will be very clean looking on the cylinder affected, the coolant acts as a steam cleaner on the plugs.

Nice tip Bruce, those of us who do not work on this stuff on a daily basis can always use a tip or two

I have a Ratson pickmeuptruck with a head gasket problem. This spring, I'll have a look at it.

[W1UJR]

Even more here Terry, we call it our "Wall of Fame" page, some of best of the worst things we have found...and fixed.

http://atlanticmotorcar.com/service_solutions.htm

A Few Previews

[W3SLK]

Perfect timing Bruce. I was just discussing that very case at work. You see, we make 'bio-diesel' from algae. I never gave it much thought though. I always thought the 'rainbow sheen' that you saw close to water shore was from decaying plant matter. Our next move is to make oil that will be used in cooking. Not as a heat medium, (like a deep fryer), but to be added dry to a cake mix so that all you do is add water!

[W1UJR]

Bob - That's great, simple answer is usually right, and very happy to hear that all is well.

Mike - I should have labeled the photos, but you nailed it, bad bio-diesel, in this case made from "animal renderings"...yuck, a most nasty job for the tech to scoop out and clean the fuel tank.

The other photos were:

- VW Passat Diesel engine not run on proper oil, wore holes through the top of the cam followers, was traded into a local dealer and brought our facility to diagnose

- Jaguar XJS V12 engine, replacement of valve cover gaskets, something like 20+ hours when the additional time replace dry rotted vacuum lines and hoses was factored in.

- BMW 328XI "N" engine with a defective electric water pump, yes, BMW drives the water pump by electrical means, in this case a defective seal did a world of hurt

- BMW Z3 - Left off my favorite of all time, when a mouse made a nest and chewed through EVAP hoses on the top of the fuel tank on, had to drop the rear suspension and driveline out to remove the tank.

[WA1GFZ]

Cars of today are some of the poorest designed HOS known to man.
I guess the more they cost, the worse the design.
Bruce must enjoy handing the bill to some clueless yuppie.
I had to take 1/2 your car apart to change this $.50 hose.

[W1UJR]

Cars of today are some of the poorest designed HOS known to man.
I guess the more they cost, the worse the design.
Bruce must enjoy handing the bill to some clueless yuppie.
I had to take 1/2 your car apart to change this $.50 hose.

Not too many Yuppies in Maine, a little too rural to be urban, but we do have some very nice folks to deal with, and who liked their cars repaired correctly...and frankly there are just not too many options for that.

Funny thing is that as I write this I am in Raleigh, NC doing a seminar at a shop which works on Acura, Honda and Toyota and Lexus...and I'm shocked by some of THEIR bills, guess you catch it both ways with newer cars.

Here's a few images of the "smoke machine" pushing out smoke from the damaged hose during our testing process, my scary white leg in the background. That mouse was sure hungry...