BX24 - Won't Start

[Ngiovan]

Hi all,

Just got my BX24 home today and started some diagnostics. For more background on the purchase, check out this thread.

Pulled the glow plugs (pics attached) and ran a compression test on each cylinder.

• Cyl. 1 (frontmost) came in just a shade under 200psi
• Cyl. 2 (middle) jumped up to about 600psi when cranking, but would not hold a reading at all. Just bled out
• Cyl. 3 (rearmost) read up to about 400psi but also bled right out

I saw a few recommendations on checking intake/exhaust for leakage there, or diving into the valvetrain to see if clearances are out of spec.

Any ideas on where to go next?

 

[85Hokie]

The 200 is way low ............. surprised that it DID start when it did.

NOW 600 is crazy high - 420 is low min - and max should be something close to 450+

YOU ran a compression test? OR a leak down test? If a compression - the gauge is bad IF it leaked down!!!

IF leak down - you needed to have each at TDC to get accurate reading..... and 600 psi is very high.

 

[North Idaho Wolfman]

Pull the motor and start tearing it down.
You more than likely have a broken piston or a bent rod.

 

[Ngiovan]

The 200 is way low ............. surprised that it DID start when it did.

NOW 600 is crazy high - 420 is low min - and max should be something close to 450+

YOU ran a compression test? OR a leak down test? If a compression - the gauge is bad IF it leaked down!!!

IF leak down - you needed to have each at TDC to get accurate reading..... and 600 psi is very high.

Thanks for the feedback!

A compression test is what I attempted. Got a diesel-specific kit with the correct fittings into the glow plugs.

After your comment I went back and ran again and getting pretty much nothing on all 3 cyl.

I'm thinking I'll start by taking the head off tomorrow and see if there's any further damage.

Thanks!

 

[Ngiovan]

Pull the motor and start tearing it down.
You more than likely have a broken piston or a bent rod.

That was my expectation going into the purchase, but wanted to make sure I checked all the diagnostic boxes once I brought it home.

Thanks!

 

[Ngiovan]

Checked valve clearances today, they seem awfully tight. From what I could find for the D902 it should be .145-.185
Cyl 1

• .01 Intake
• .01 Exhaust

Cyl 2

• .008 Intake
• .014 Exhaust

Cyl 3

• .01 Intake
• .008 Exhaust

With the glow plugs out I can freely turn the flywheel by hand. On each valve I checked at the most closed position I could find. Even on cyl 1 at TDC I had to go another 30 or so degrees just to get the feeler in there.

I know I'm gonna end up pulling the head off anyhow, but this just seems way out of spec. Worth investigating further, or just tear it down?

 

[North Idaho Wolfman]

Checked valve clearances today, they seem awfully tight. From what I could find for the D902 it should be .145-.185
Cyl 1

• .01 Intake
• .01 Exhaust

Cyl 2

• .008 Intake
• .014 Exhaust

Cyl 3

• .01 Intake
• .008 Exhaust

With the glow plugs out I can freely turn the flywheel by hand. On each valve I checked at the most closed position I could find. Even on cyl 1 at TDC I had to go another 30 or so degrees just to get the feeler in there.

I know I'm gonna end up pulling the head off anyhow, but this just seems way out of spec. Worth investigating further, or just tear it down?

You do know it's .145 - .185 mm or 0.00571 to 0.00728 in.

Are you swapping mm to in?
Because .008 mm seams just about impossible to measure?
It would be .00031496063 inches

 

[Ngiovan]

You do know it's .145 - .185 mm or 0.00571 to 0.00728 in.

Are you swapping mm to in?
Because .008 mm seams just about impossible to measure?
It would be .00031496063 inches

You're spot on. Misread the sizing as mm and it's inches

 

[Ngiovan]

Is there a way to pull the head without removing the rockers/valve springs?

 

[GreensvilleJay]

I would say yes.....looked at K online parts to see, it's similar to the BX23S engine design.
Just be SURE to take LOTS of pictures before and during , so you KNOW where stuff goes when you reassemble ! One picture could save you 1,000 '4 letter words'....

 

[eserv]

Is there a way to pull the head without removing the rockers/valve springs?

You will need to remove the rocker shaft but not the valve springs. It is good practice to keep the pushrods in the same place you removed them from. You can't remove all the head bolts with the rocker shaft in place.

 

[Ngiovan]

You will need to remove the rocker shaft but not the valve springs. It is good practice to keep the pushrods in the same place you removed them from. You can't remove all the head bolts with the rocker shaft in place.

Perfect, that's how I went about it. Thanks!

 

[eserv]

Perfect, that's how I went about it. Thanks!

Now that you have the head off you should check the piston protrusion (amount they stick up above the block at top dead center) Should be about .020"

 

[Ngiovan]

Now that you have the head off you should check the piston protrusion (amount they stick up above the block at top dead center) Should be about .020"

That was my next question. Also going to upload a few pics of each cyl and the head.

 

[Ngiovan]

Adding some pics of the head and each cyl at the top of their stroke. Checking protrusion now.

Thanks for all the feedback!

 

[85Hokie]

The carbon build up is rather healthy. Or is that oil coated?

Not sure if there will protrusion unless block was shaved.

Tell us how you plan on measuring that piston protrusion? What tool?

 

[eserv]

The carbon build up is rather healthy.

Not sure if there will protrusion unless block was shaved.

Tell us how you plan on measuring that piston protrusion? What tool?

To check it I use a straightedge across the piston and a feeler guage from it to the block surface. If you don't have about .020" protrusion a D902 will be very hard to start.

 

[85Hokie]

To check it I use a straightedge across the piston and a feeler guage from it to the block surface. If you don't have about .020" protrusion a D902 will be very hard to start.

Gonna have to clean those pistons first!

There has to be a couple of thou oil/carbon on them!

 

[Ngiovan]

To check it I use a straightedge across the piston and a feeler guage from it to the block surface. If you don't have about .020" protrusion a D902 will be very hard to start.

I was thinking with a caliper, I have feelers too though

 

[eserv]

I was thinking with a caliper, I have feelers too though

Just because I do it a certain way doesn't make it the only way! Caliper should give a good indication.