EDITED AND UPDATED

Hi all!

For the last 24 hours I have been the proud owner of a 2005 Mazda B4000 Bravo 2x4 Automatic or Ford Ranger, as you like to call it. The pride took a little hit about 2 hours into my ownership, when the engine blew up. Yes, it is kinda my fault. I knew, that the car had a head gasket issue producing small amounts of mayonnaise in the oil and coolant. From the seller to my home I had about 20 miles to go so I did a quick oil change and hoped for the best. Well, the best never came. My eyes never left the thermostat and the oil warning light but neither the light came on nor did the water temperature even think about leaving the OK region, when suddenly...tick tick tick... I switched it off before the tock tock tock...

Opening the hood you could feel the heat radiating from the engine but the radiator was almost cool. THERMOSTAT? The valve train is now full of hot mayo...AWESOME!

Also, any idea about the root cause? The engine has only done 60000 mls and used by elderly people. The rest of the car (a 2+2) is in pristine condition (and I only paid US$1600) and fully loaded.

Why did the temp not indicate and the radiator stay cool?
Why was the oil cooler cool to the touch with the engine burning up?
A mechanic said to the previous owner "...your problem is the oil cooler pump..." Asked about it, the owner confidently said "I can show you!" and pointed in the direction of the steering rack to the left of the radiator. HUH?

Will have a look today how bad it is,

Any help is much appreciated...

Cheers, Thomas / Brisbane Qld

 

The root cause likely was an engine overheating episode.
Did the "elderly people" maintain the vehicle properly? The truck could've been soldiering on with its factory fill in the crankcase.
How did the oil look when you drained it?

Had the cooling system ever been serviced?
17 years of haphazard coolant top-offs (using Dex-Cool variants -of which there are many) can easily cause sludging.
NOTE: The Dex-Cool formulae are designed for sealed systems ONLY.
The coolant reservoirs on these vehicles isn't sealed. They're open to the air.
Jokers pour Dex-Cool into any system because they don't know/care. When the system clogs, they call it "Death-Cool" because they're clever.

Thermostats can fail.

Sometimes the impellor in a water pump erodes away.

Does the plastic thermostat housing leak? They split along a seam, as the one in my 2005 had, and could've leaked out coolant thus damaging the engine.
NOTE: The PO of my truck was aware, caught the leaking part and had it replaced years before I bought the vehicle from him.
There are solid metal replacements available should that problem come up with yours.

I looked at my truck to see if there's an oil cooler "to the left of the radiator" and there is none.
The transmission cooling lines go into the radiator's left tank. The cooling lines are also "Tee'd" into an auxiliary, external cooler on the right side ahead of the AC condenser, in the airspace behind the grille).
I have no oil cooler in my 4.0l SOHC but Mazda could've added one for the Aussie market.
Is there a chance the mechanic was being rude to the elders?

Re the temp gauge: The 12v sender unit can go bad.
My 2005 has both a sender (12 volts for the dashboard gauge) and a sensor (5 volts used to report temp to the ECU).
Does yours have both as mine does? Mine are side-by-side in the aforementioned plastic thermostat housing.
Remember, they're two different parts.

​​​​​​​Hear from you, George / Hackensack NJ

 

Thanks George, you are a legend, great writeup.
All true and I will check all of it. The lady i bought it off got it from an elderly couple, teachers who taught in the outback. So they drive to a school, pretty much stay there for a year, that's where the low km are from. But true, probably not much pristine servicing. She bought it 18 months ago and paid $12500, I just paid $2500 (all Australian). I hope the engine didn't take too much damage, I will slowly take the heads of (all new to me, I prefer bikes) and see what's what. I have had a look around and I can get a lowish 120000km engine for $3700... outch. No idea what a complete rebuilt would cost but let's hope neither is necessary.

You are probably right about he "oil" cooler, ie transmission oil... I knew about the problem so I did an oil change at the seller's place (milk coffee) and thought I would be ok. In hindsight not so clever... Anyway, the seller was driving and when she heard a pop, she immediately stopped. After a day of consideration I noticed that the pop was the airbox lid that was pressurised and popped off... It was tow truck after that so fingers crossed. The tow truck driver wanted to buy the vehicle, that's how good it looks...

I turned it over by hand yesterday and all seems smooth. Will see if I can get a manual somewhere and then start digging in. Will update.

Thanks again. T

 

Started yesterday but didn't make much of a dent. Another thing that makes this a bit difficult is that my car has an aftermarket LPG option. I don't know if you guys have that over there, before electric came along, all taxis over here ran on cheap LPG so some people got that too. So I am dealing with another layer of hoses, electronics and whatever. Oh well, it's only LPG, what could possibly go wrong?

I did make a discovery though. This car (maybe all?) has one of those sandwich style oilcoolers. This should be plumbed into the radiator but it's not connected at all. So I wonder if that turned into the problem with the "oil cooler pump" mentioned earlier...? Anyway, I am getting there... slowly.

 

Just out of curiosity:
Are you going to use the LPG feature?
I knew a guy who's dad owned a rural farm supply and hardware store. Agway was the name; if you're into Americana.
He had a long flatbed Ford truck which had LPG fitted. He sold LPG and once the engine was started on gasoline/petrol, it'd be switched over to LPG.
A friend bought the truck when it became available.
Some fleet vehicles and national park trolleys were LPG here but I do believe they weren't sold to the general public.

Also, the oil filter in my 4.0l Ranger has very little air space around it. I wonder if the add-on sandwich necessitated the use of a smaller filter?
While that's not the end of the world if done correctly, real cheap, ersatz filters may have been sourced by the buffoon who did the incomplete cooler installation.

 

Hi George,
what you described is exactly how it works. You start on Petrol and then switch to LPG. I would like to give it a try. Prices here atm are about $1.15/liter of LPG and $2/liter of Petrol. That's Australian dollars. I don't know if 1L LPG gets you exactly as far or even further than 1L of Petrol.
They are definitely phasing LPG out because of big bad climate change BS. There are actually some cars, especially 4.0 I6 Ford Falcon Utes that run exclusively on LPG...
But I am pretty sure that when I have repaired this car, internal combustion engines will have been outlawed and we all are Fred Flintstone-ing it... except for the important people, of course.
Cheers,
Thomas