Hi, my 240 whilst driving started to misfire terribly. Big popping sounds coming from the engine bay. I noticed it was only when going uphill (any % uphill). As I’m driving home trying to make it it was seriously losing power. I pulled over to check the engine bay as was getting hot. All seemed fine.

Took the car out of park and into drive and then it stalls, followed by a bang and puff of smoke from the engine bay.

I’ve been told it’s the core plug that’s blown out. Any reason why it would have done that. And is it. Relatively easy fix?

it’s a tight space between the firewall and engine so can’t get any swing from tools etc.

thank you.


1986 2.3L 240

 

Clean your flame trap. When it gets clogged pressure can build up in the crankcase blowing out the cam plug. How many miles do you have on your engine? I don't think that would cause popping and backfiring though. You may want to check if your timing belt slipped a tooth.

 

A "core plug" usually refers to the casting plugs (used in manufacturing) found in cast iron blocks. In the b230 block picture below you see 4 plugs on the exhaust side of the block and none visible on top of the rear of the block. There is a core plug hidden behind the flywheel - which would require trans or engine removal to get to. If a core plug leaks you will lose all of the coolant and the engine will over heat. Did that happen?

There is a cam plug used on the B230 240 head where a distributor covers that space on the 940s. That metal/rubber coated plug can pop out due to higher than normal pcv pressure as another has mentioned. When that plug pops out - oil will leak profusely out that open hole. Did that happen?
A cam plug is a simple repair. You will need a new cam cover gasket, a new cam plug and a couple of drops of silicone to seal the cam cover gasket where it has to bend.

That does not explain - "misfires, popping sounds, loosing power, stalling, bang and a puff of smoke".

Those symptoms could easily be caused by running the engine out of oil until it seized/self destructed (from a missing cam plug) or frying/overheating the engine (due to lack of coolant).

The solution to either of those is much more than just a "core plug".

Sorry for your loss.

 

arround 400-450k

 

Just to clarify what Honk posted. Is it a freeze plug that blew out or was it the cam plug? If it is a freeze plug as Honk said then he's correct in that the engine is probably shot.

 

 

Never heard of a core plug. If you look at the block that Honk posted you'll see there are not plugs between the block and the firewall. Given this, I assume that you mean the cam plug a it is between the head and the firewall. That is what I was referring to in my first post. If this blew out you would see a lot of oil in your engine compartment up by the firewall.

If it were me I would check the flame trap to see if it is clogged. I would also perform a compression check. You have a lot of miles on your engine and the compression may be down which results in blow-by around your pistons. Was there any oil left in the engine?

 

Unfortunately there are 2 smaller core plugs on the back (and front) of the b230 head.

 

Yeah - what still isn't clear on this thread is whether it was a freeze plug that blew out or the cam plug. The cam plug goes where the hole is shown on the picture of the head. I haven't seen a freeze plug blow out before. I have seen leaks in them due to rust. Cam plugs blow out all of the time - especially on high mileage engines.