Fire from the inlet manifold

[shaf]

Hi all

Restoring a 280 sl just replaced it with a second hand engine which I was told was a rebuild. The car wants to start but there is petrol coming out of the inlet manifold which flames up in fire before a big bang have checked the timing and firing order

Shaf

[enochbell]

Shaf,

You could start by disconnecting the CSV on the intake manifold: just remove one of the wires.  It may be stuck open and causing too much raw gas and flooding as you are starting the car.

However, I suspect that is not the problem, because if you have ignited gas and "boom" then you may have a potential valve issue, like maybe ignition is occuring with an open intake valve.  I have seen it before when someone who did not pay attention adjusted the valves out of sequence and actually burned a VW to the ground by finally getting it started but...

Check the valves carefully.

Have a fire extinguisher at hand.

g

'64 230sl, fully sorted out...ooops, spoke too soon

[glennard]

Hi, Rebuilt???  By Whom??  Before I ran the engine, I would 1)check the valve clearances- .003 and .007. 2)Check the cam/crank sync/timing, 3)Do a compression test 4)Injection pump timing and on and on-------------.   The PUB(Pagoda University Blacklick) is your best resource!!   A new 'rebuilt' engine has all sorts of gremlin possibilities.

[al_lieffring]

quote:Originally posted by glennard

Hi, Rebuilt???  By Whom??  Before I ran the engine, I would 1)check the valve clearances- .003 and .007. 2)Check the cam/crank sync/timing, 3)Do a compression test 4)Injection pump timing and on and on-------------.   The PUB(Pagoda University Blacklick) is your best resource!!   A new 'rebuilt' engine has all sorts of gremlin possibilities.

I agree with the above, except for the order, Always test the compression first. (preferably before buying the motor, but it's too late for that now)

low compression, check valve clearance etc, Good (even) compression check distributor timing leaky cold start injector etc

good luck
Al

Al Lieffring
66 230Sl
Jones'n for a new gas tank

[ja17]

Hello shaf,

Assuming that the engine was runable when installed, I agree with Greg (enochbell) the starting valve may be stuck open. In addition if the injection lines are not primed up it may take quite a bit of cranking. If this is the case the engine  will be trying to start "lean" causing an intake backfire even though the cold start valve may be dumping fuel and causing the intake fire. It is not uncommon for these engines to "cough" or even backfire through the intake if a lean situation occurs.
Crack open the injector lines at the injectors to see when fuel arrives then tighten the lines. You may need a fresh set of plugs at this point if the originals become fouled from the previous starting process.

Joe Alexander
Blacklick, Ohio