Overheating and White Smoke
Thread Starter
Newbie
Joined: Jun 2020
Posts: 5
Likes: 2
From: New Brunswick, Canada
240D
Overheating and White Smoke
Ol" Lizzie (1974 240D) has started "chugging" and white smoke puffing from exhaust right from startup. When it does this (sometimes it doesn't do it at all) it BADLY lacks power.
Prior to this I can hear hissing from near the newer radiator cap when full. Antifreeze does seem leak a bit from the radiator and I believe that it's slow leaky. Temp rises really fast and wants to peg. No heat as well.
Would that be the source of this problem? Is this a massive air lock? I can purge air from screw on top the thermostat and the temp will fall right back to where it should be, but then it continues to rise to near pegged once again. Also I can get good heat when the air is removed.
When it doesn't do this, it runs like a top.
What do you all think? I hope I can save her!
Thanks in advance.
Prior to this I can hear hissing from near the newer radiator cap when full. Antifreeze does seem leak a bit from the radiator and I believe that it's slow leaky. Temp rises really fast and wants to peg. No heat as well.
Would that be the source of this problem? Is this a massive air lock? I can purge air from screw on top the thermostat and the temp will fall right back to where it should be, but then it continues to rise to near pegged once again. Also I can get good heat when the air is removed.
When it doesn't do this, it runs like a top.
What do you all think? I hope I can save her!
Thanks in advance.
Senior Member
Joined: Mar 2017
Posts: 258
Likes: 50
R320, Astro, JSW, ST4
Since this car is pre-EGR, there's no EGR cooler to leak coolant into the intake.
So, I suspect a head gasket leak. Don't like being the bearer of bad news, but that's my first guess.
Did it get overheated before, and now is leaking?
Usually with this, the pressure when running would allow exhaust gases to push into water jacket.
If bad enough coolant can seep back into cylinder(s) at rest.
The high pressure exhaust can introduce a bubble into the coolant hoses / heater hoses / block such that the gauge is all over the place jumping.
Burping the air out of the system would then be a temporary fix until more combustion gases comes into the block from the gasket leak, then gauge goes crazy again.
So, you can also have this situation of no cabin heat, but engine overheating.
White smoke at startup, from coolant leaking back into motor.
No power because you're boiling coolant in the cylinder and that robs heat/energy... and misfiring/skipping.
Sound right?
You can confirm this for sure with a diesel exhaust tester (it attaches to the coolant reservoir or top of radiator like with a rubber cork).
Most commonly the test kit had testing fluid for gasoline motors, but you can get the correct fluid for diesel exhaust gases.
Your car's system will probably also allow you to just leave it running with cap off, and when the thermostat opens up and coolant is flowing across the radiator, just look for air bubbles in the coolant.
They would be coming from the leak.
So, I suspect a head gasket leak. Don't like being the bearer of bad news, but that's my first guess.
Did it get overheated before, and now is leaking?
Usually with this, the pressure when running would allow exhaust gases to push into water jacket.
If bad enough coolant can seep back into cylinder(s) at rest.
The high pressure exhaust can introduce a bubble into the coolant hoses / heater hoses / block such that the gauge is all over the place jumping.
Burping the air out of the system would then be a temporary fix until more combustion gases comes into the block from the gasket leak, then gauge goes crazy again.
So, you can also have this situation of no cabin heat, but engine overheating.
White smoke at startup, from coolant leaking back into motor.
No power because you're boiling coolant in the cylinder and that robs heat/energy... and misfiring/skipping.
Sound right?
You can confirm this for sure with a diesel exhaust tester (it attaches to the coolant reservoir or top of radiator like with a rubber cork).
Most commonly the test kit had testing fluid for gasoline motors, but you can get the correct fluid for diesel exhaust gases.
Your car's system will probably also allow you to just leave it running with cap off, and when the thermostat opens up and coolant is flowing across the radiator, just look for air bubbles in the coolant.
They would be coming from the leak.
Last edited by B34chBum; Jul 6, 2020 at 05:12 PM.
MBWorld Fanatic!
Joined: Jan 2016
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Likes: 880
From: In the Shadow of the Tetons
2013 ML350 Bluetec
'nuther vote for head gasket.
Does your upper radiator hose remain somewhat hard (pressurized) even after cooling down overnight? If you relieve the pressure in the radiator with the engine HOT, is the upper radiator hose collapsed after cooling down overnight?
Does your upper radiator hose remain somewhat hard (pressurized) even after cooling down overnight? If you relieve the pressure in the radiator with the engine HOT, is the upper radiator hose collapsed after cooling down overnight?
Thread Starter
Newbie
Joined: Jun 2020
Posts: 5
Likes: 2
From: New Brunswick, Canada
240D
Thanks for the replies!
It was not overheated before by me. I will check out the hoses next time I'm out there. I do believe there is a bubble in the coolant because I try to burp the system but I don't have a hill to get it on. You are right because when I do that, it gets heat back and runs perfect. I tried running her today and eventually the convulsions and white smoke and miss eventually stopped after running it for maybe :30. I went back out hours later and it still ran good. However, I think it's going to do it again when I go back out another day.
Could a faulty radiator cause this? The only reason why I ask is because it there's antifreeze sitting down at the bottom where it sits in.
one other thing...I have a radiator cap with the red lever on it. When it runs the way it should, when I open that lever it starts convulsing.
When I shut the car off today... smoke was coming from the hose connected to the radiator (slim vent hose?)
It was not overheated before by me. I will check out the hoses next time I'm out there. I do believe there is a bubble in the coolant because I try to burp the system but I don't have a hill to get it on. You are right because when I do that, it gets heat back and runs perfect. I tried running her today and eventually the convulsions and white smoke and miss eventually stopped after running it for maybe :30. I went back out hours later and it still ran good. However, I think it's going to do it again when I go back out another day.
Could a faulty radiator cause this? The only reason why I ask is because it there's antifreeze sitting down at the bottom where it sits in.
one other thing...I have a radiator cap with the red lever on it. When it runs the way it should, when I open that lever it starts convulsing.
When I shut the car off today... smoke was coming from the hose connected to the radiator (slim vent hose?)
Thread Starter
Newbie
Joined: Jun 2020
Posts: 5
Likes: 2
From: New Brunswick, Canada
240D
Okay you all, I finally got some time to get under the hood (actually took it completely off) and my uncle and I got the head gasket replaced. Bolted her all back up and it purred like a kitten... until we introduced antifreeze to it. We put some in the radiator and it began to run very rough and a cloud of thin white steam poured out the exhaust!
The temp on the dash shot up to max within a few short minutes. It doesn’t feel “hot” like it’s going to overhear when your looking at the motor.
We didn’t tighten up the exhaust manifold bolts fully just yet, but we could see that antifreeze is definitely coming out down through the exhaust. That to me explains the thin white steam.
Whenever the engine needs to pressurize with coolant it freaks out. Running rough and white steam all out the exhaust. If you leave the rad cap off or something to reduce the pressure... it runs perfectly.
One other thing that was noticed is that the valve on cylinder number one had slight antifreeze on it when we turned it upside down. The others were dry. The head gasket did not seem to show anyplace where it was “blown out”.
Any ideas as to what’s going on? At this point I’m trying to determine if it’s definitely a crack in the cylinder head and NOT the block. Or maybe it’s neither?
Thanks.
The temp on the dash shot up to max within a few short minutes. It doesn’t feel “hot” like it’s going to overhear when your looking at the motor.
We didn’t tighten up the exhaust manifold bolts fully just yet, but we could see that antifreeze is definitely coming out down through the exhaust. That to me explains the thin white steam.
Whenever the engine needs to pressurize with coolant it freaks out. Running rough and white steam all out the exhaust. If you leave the rad cap off or something to reduce the pressure... it runs perfectly.
One other thing that was noticed is that the valve on cylinder number one had slight antifreeze on it when we turned it upside down. The others were dry. The head gasket did not seem to show anyplace where it was “blown out”.
Any ideas as to what’s going on? At this point I’m trying to determine if it’s definitely a crack in the cylinder head and NOT the block. Or maybe it’s neither?
Thanks.
Thread Starter
Newbie
Joined: Jun 2020
Posts: 5
Likes: 2
From: New Brunswick, Canada
240D
I wrote that incorrectly I guess...
The car was started to check to see if the timing was right and if it even ran. It was then primed started and then coolant was filled. It was NOT driven anywhere nor ran for more than a minute or two before antifreeze was put in..
We’ve came to the conclusion that the coolant is not reaching the block. Coolant it’s pushing back up out the radiator.
Could the radiator be bad? If it is, does anyone know of a radiator cross reference I can get from rock auto or somewhere?
What do you guys think about a bad water pump?
The car was started to check to see if the timing was right and if it even ran. It was then primed started and then coolant was filled. It was NOT driven anywhere nor ran for more than a minute or two before antifreeze was put in..
We’ve came to the conclusion that the coolant is not reaching the block. Coolant it’s pushing back up out the radiator.
Could the radiator be bad? If it is, does anyone know of a radiator cross reference I can get from rock auto or somewhere?
What do you guys think about a bad water pump?
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