L400 - headgasket? cracked head? other?

[lopar]

Ok, here's the low down.......... I have a 1994 L400 and was driving up island (as I often due). I was going down hill about 5km north of Ladysmith and just starting to lean back into the throttle, 90km ish.

Best description: seemed like I lost a cylinder and big heepum cloud of smoke behind me, mostly white "ish", and a slightly more than normal knocking sound.

Had it pulled off the road and turned off less than 10 sec and gave it a good look over....... coolant reservoir full, oil good (full, no bubbles or smells) no obvious leaks of any fluids.

Flashed it up (less than 2 seconds) and got a big heepum cloud of white out the exhaust.

That was enough for me, convinced at the very least that I have coolant burning through the cylinders: had it towed.

Head has not been removed yet; at this point I am hoping and praying that it is just some freaky head gasket blow out with worse cases being cracked head and or blown cylinder sleeve or something like that.

NOTE: most all components of the coolant system replaced new several days prior; absolutely no engine problems prior

Any wagers, at my expense , or guesses on what is most likely the cause and or effect before the head comes off? Comments? Thoughts? advice?

As always, thanks for comments and advice.........

Cheers,

Chris

[jessef]

After asking around, the only other 4M40 (L400) engine that I've heard of with coolant passing into the cylinders was a crack in the head and not the gasket itself.

But if the gasket had a weak spot, it could pull the coolant through there and out the cyl.

Head needs to come off either way to see unfortunately.

[MardyDelica]

Hi, chris,
before you take out the head make sure you have a spare cyl head & head gasket ready.
sometime this problem occur in japan i already have one L400 that i did replace the cyl head.
did service the vehicle but with in a week it started to go.
open it up & see the head is crack . this is due crack already in japan so very hard. some car in japan you dont know if the previuos owner had overheat this vehicle.
after changing it everthing went well
i might have soem cyl head coming next few month
just keep in contact with me
Cheers;
mardy

[lopar]

Thanks for comments so far.

I have also been doing some digging and leaning more towards cracked head......

Every last finger points to coolant system problems.... back to my original comments, "coolant system replaced almost entirely" several days before hand. No problems before at all, coolant system components replaced purely on spec and preventative maintance.

What would be the most likely component failure to cause this...... i am thinking thermostat or waterpump? No point in replacing cracked head if I still have a faulty coolant component.

Cheers,

Chris

[FalcoColumbarius]

This topic has been moved from General Discussion to L400 Technical.

Falco.

[jessef]

It is an odd coincidence that it happened right after your coolant system replacement/servicing.

I wonder if there was a large enough pocket of air trapped or the new rad or thermostat was blocking coolant flow.

I would look at these components to rule them out.

[lopar]

It is an odd coincidence that it happened right after your coolant system replacement/servicing.

I wonder if there was a large enough pocket of air trapped or the new rad or thermostat was blocking coolant flow.

I would look at these components to rule them out.

I was thinking along the same lines....... the irony of course, was after I picked it up after the work was done, we had a foreshadowing conversation at the shop of such a thing potentially happenning from faulty components and/or air pockets and such. Reputable shop though, I do not expect any problems. I am sure they can claim uphill for faulty component.

Question though..... if there is an air pocket from the beginning, will that prevent fluid from being drawn from the overflow? The overflow/reservoir was fully, but the way the rad is setup, rad could have been bone dry for all I know...... cap at overflow versus others at the top of rad.

Cheers,

Chris

[MardyDelica]

hi, Chris.
as i mention to you, we never know the history of this car.
not all cars came from japan is good were are all leaning on the luck.
air pocket or whatever you call it wont create problem on your cyl head.
it must be cause by a previous owner who dont service the vehicle.
thermosthat & radiator could also be a factor if you dont replace it. water pump you will know it rightaway if no sign of circulation.
very simple to diagnose for this.it a matter of how you understand to make this engine work good.
its just sad this thing happen to you when you just purchase it.
its expensive to fix this not cheap.
try to keep in touch later when i cmae back maybe i can help you with this;
Cheers;
Mardy

[dfnder]

If your rad cap isn't working proper it could be preventing reverse flow into your rad from the overflow.