- Joined
- Dec 8, 2025
- Messages
- 2
- Points
- 1
- City
- Corvallis
- State - Country
- OR - USA
- Vehicle Year
- 1999
- Vehicle
- Ford Ranger
- Drive
- 4WD
- Engine
- 4.0L
- Transmission
- Automatic
- Tire Size
- 29in
Context: recently purchased a 1999 Mazda b4000. It was minimally driven in the last year, just to get the fluids moving, due to the previous owner’s health declining. Service history of regular oil changes and maintenance. New radiator and water pump in the last 1.5 years.
It has a dull knock when it cranks before starting, burns a little coolant on startup (hardly white smoke, concluded this based on smell) and no more coolant burning after a longer drive, doesn’t overheat, and sometimes has a coolant leak at the front of the engine. I performed a combustion leak test which came back negative (no combustion gases in the coolant). It has a vacuum leak (20% long term fuel trim, intermittent seeking idle in park).
Coolant leak at front of the engine doesn’t always occur but when it was happening, I couldn’t tell if it was coming from the water pump, timing cover, or somewhere else. I’ll add some photos that I was able to get. From reading, it seems a bad lower intake manifold could be responsible for the vacuum leak + coolant entering cylinders.
Have I ruled out a bad head gasket or cracked block with the combustion leak test or should I do more (compression test) to confirm?
Do I move forward with the lower intake gasket to inspect/confirm things and/or do a coolant pressure test to deduce where external leaks are? Is it possible the vacuum and coolant issues separate and I’m assuming the worst?
I want to do things the right way and not just tear a bunch of stuff apart and throw parts at it. I’m new to this level of engine work, so I’m not quite sure what the most efficient/logical next step is. Thanks
It has a dull knock when it cranks before starting, burns a little coolant on startup (hardly white smoke, concluded this based on smell) and no more coolant burning after a longer drive, doesn’t overheat, and sometimes has a coolant leak at the front of the engine. I performed a combustion leak test which came back negative (no combustion gases in the coolant). It has a vacuum leak (20% long term fuel trim, intermittent seeking idle in park).
Coolant leak at front of the engine doesn’t always occur but when it was happening, I couldn’t tell if it was coming from the water pump, timing cover, or somewhere else. I’ll add some photos that I was able to get. From reading, it seems a bad lower intake manifold could be responsible for the vacuum leak + coolant entering cylinders.
Have I ruled out a bad head gasket or cracked block with the combustion leak test or should I do more (compression test) to confirm?
Do I move forward with the lower intake gasket to inspect/confirm things and/or do a coolant pressure test to deduce where external leaks are? Is it possible the vacuum and coolant issues separate and I’m assuming the worst?
I want to do things the right way and not just tear a bunch of stuff apart and throw parts at it. I’m new to this level of engine work, so I’m not quite sure what the most efficient/logical next step is. Thanks
