Head Gasket Failure: Get Help Now!

Hi.

"The head gasket on my Volvo TDi (5-cylinder - AEL engine) has failed. I noticed it during a vacation trip on German highways, while driving at higher speeds - there was high pressure in the cooling system, but no thermal overload. Fortunately, it survived the 3500km vacation trip. Now that I'm back home, I did a CO2 test, which was very positive, so I immediately removed the cylinder head."
The fault was the same and easy to identify: cylinder 4 is leaking on both sides. This is strange, considering the engine has only 200,000 km (approximately 124,000 miles) on it, and this type of issue is quite rare for this engine.

Here's my question: When I cleaned the head and then removed the injectors, I immediately noticed that one of the injectors (NHG) was positioned slightly lower than the others. This suspicion was confirmed when I couldn't find a seal on that injector. I'm not sure how it could have been sealing in the first place. My question is: Could this be the cause of my problem? Could the injector being 2-3mm too deep lead to incorrect fuel injection, potentially causing higher temperatures and, consequently, a leaky cylinder? I've checked all the injectors, and they appear to be functioning perfectly based on their appearance and opening pressure.

"Another question - I installed a 3-hole gasket. Is it really true that it was already installed from the factory? I always thought that if you have the head removed, like in this case, you need a stronger gasket. The engine mechanic said that it's not really possible to remove the head completely anyway; he can only remove a very small amount of material so that the surface is smooth again. The area where it's leaking is already uneven. So, he said, if you're using a 3-hole gasket, then you should stick with a 3-hole gasket, because it's about the piston protrusion, which doesn't change. He said that removing a minimal amount of material from the head wouldn't have any effect on the engine, and that it's fine as is."

Do you see it that way too?

Thank you.

best regards, uwe

How many times do I have to write this?!

The seals are selected based on the piston protrusion.

It has absolutely nothing to do with designs created from scratch (which, according to the manufacturer, is not even allowed ).
When planning this modification, the valve seats must be machined deeper to prevent collisions.

And yes, it's perfectly normal for the 3-hole version to be installed from the factory.


I doubt that the ZKD (cylinder head gasket) damage is related to the injector. It wouldn't cause earlier injection/ignition, nor would it increase combustion pressure in the cylinder in any other way.

I would consider it normal for the timing chain tensioner (ZKD) to fail after 18 years, and it's also not uncommon for the mileage to be inaccurate at that age.
Everything has been said about the 3-hole .
Get new O-rings for the injectors, properly adjust the fuel injection timing, and look forward to the next 200,000 km.

Best regards,

Hi.

Thank you for your help. The engine is from 2005 and is a replacement engine. Yes, of course, it can happen, but I still think it's strange.

Today I ground the valves, cleaned everything, and reassembled the cylinder head. The gasket is still missing, but then everything will be put back together.

I've found something else "new" and strange, and it's making me think.

At VOLVO, there were two generations of the engine, and I'm not exactly sure how the difference is "called" - you usually notice it by the engine control unit (MSA15.7/MSA15.). I've also noticed it by the crankshaft, which is different - the part where the timing belt pulley goes on is different, and the old one doesn't fit - when I needed a replacement once. It's not a big deal, but the new engine, according to the spare parts catalog, has different injectors.

The following nozzles should fit the "newer" engine: "DSLA 93 P 838" => 5 pieces (MSA 15.8, spray angle 160°).
For the old engine, the following applies: "DSLA 150 P 502" => 5 pieces (MSA 15.7, spray angle 150°).

Now I've installed the newer engine, and the block has been replaced, but the injectors are marked "502" - so apparently, the spray angle is incorrect for this engine.

It's all very confusing – as I said, this setup has worked for 200,000 km. What should I do now? The injectors are okay, they've been tested, so they could potentially be reused – which should work again. Or could it even be that the wrong injectors are responsible for the head gasket damage? Or, to put it another way, what happens if the spray angle doesn't match the pistons, which are also different?

Speaking of pistons, I have some pistons from the old engine here - I could compare them to the ones in my engine, but I'm not sure if I'd even see a difference.

Perhaps someone has an idea – I'm at a loss. More importantly, I'm disappointed that a company doesn't consider such things – or was there even a warning from VOLVO regarding this issue that was disregarded?

Thank you.
best regards, uwe

Hello Uwe,

If the new pistons are different (e.g., have a different shape), the corresponding nozzles should also be used.
I would attribute it to the installed pistons. If the flow rate of the injectors is significantly different, you are likely to encounter even more problems: At best, the engine will run slightly better or worse; in the worst case, you may experience starting problems or rough idling.
If the replacement engine has been running normally, it should continue to do so... Regarding the head gasket: It's possible that the head gasket wasn't tightened correctly (in the right sequence or with the correct torque), or that the engine overheated (e.g., the radiator burst).

Best regards, Rainer.

Okay, thank you.

I'm probably overthinking things about that old engine. I just checked again, and the replacement part number for the pistons is the same for both engines, so while there might be different injection angles used, it apparently doesn't change anything about the engine itself. It's questionable what that actually achieves. The only thing I notice about the newer engines is that they produce significantly less soot than the older ones, which often produce a considerable amount.

He's driven 200,000 km - if the problem wasn't with the injectors or the piston, I would have suspected a different issue. However, the pistons are in excellent condition.

"I'm putting this thing together now, and hopefully I'll have some peace of mind for the next 10 years or 200,000 kilometers. When the car is 30 years old, if I have any problems, I'll know how to fix them – or I can just put in the replacement engine that's waiting in the garage."

Thank you, I'm just always so worried when something is wrong with the car - it feels like something is wrong with my child .

Regarding the ZKD (cylinder head gasket): It didn't get too hot, and the installation should have been correct from the factory. By the way, does anyone happen to have the torque specifications for the four mounting bolts used to install the cylinder head?

Hello.

Evening.
Assembly instructions and the correct order of operations are included with each new head gasket.

Sure, here is the translation of the text from German to English:

"Lg" is a German abbreviation that stands for "Liebe Grüße," which means "Best regards" or "Warm greetings" in English.

Hi,

unless otherwise noted in the poetry section:

"40 Nm, 60 Nm, then either a single 180-degree turn or two 90-degree turns using a torque wrench," the manual states.

Since ZK screws are expansion screws, they should only be used once.

Best regards from Berlin.
olli

Thank you, Olli.

Volvo specifies 35 Nm for the first stage, while Elring specifies 30 Nm (as indicated on the accompanying information sheet). Then, it specifies 60 Nm, followed by two turns of 90 degrees each – which is what I did.

And then put it all back together again...

It's a somewhat overlooked task, but disassembling, cleaning, and reassembling the head unit alone takes several hours, and then you have to clean everything else – it's tedious work that consumes a lot of time.
Then, reassemble everything: the exhaust manifolds, then the timing belts - adjust everything again. I finished preparing the cylinder head in the morning, and by 1:00 PM, the head was installed. After that, the assembly process took until 9:00 PM. A Volvo mechanic helped me after his shift, from 5:00 PM to 9:00 PM.
So, we were even there with two people...

The car started immediately and is now running perfectly again - I've only driven about 200km so far, so it still needs a bit of a "break-in" period - but I'm confident it will be fine.
Next week, we have 2000 km planned - let's see .

Besides the considerable amount of work involved, thankfully the costs were kept relatively low. The gaskets and screws cost around €100 (Elring replacement parts), and the planning cost €130 - that was it for the damage.
Of course, I immediately installed new timing belts, replaced the camshaft seals (now there are two different types, and they are TEFLON!), and, of course, used an original water pump – even though the old one had only 50,000 km on it. However, the pump belt looked like it had been in the car for 200,000 km – I have no idea what's going wrong; the teeth were coming off the belt again (and it was all dry!). Therefore, I will now only use original parts, even though the price of 45€ per belt is a bit steep. However, with my discounted price, it works out okay. If an aftermarket part deteriorates to that extent after a short time, I can only assume that it was stored improperly and is therefore old. I used Hutchinson belts before, which shouldn't be cheap belts...

Thank you for your help.
Best regards, Uwe.

Hello Uwe,

That sounds good.

Best regards, Rainer.

Hello!

Sorry, I didn't know this would work. Should I change it?

Okay, sounds good, I just hope it lasts. I'm always a bit apprehensive, but honestly, it can't be worse than THAT job. I had a 70-year-old Volvo master helping me, and he showed me everything in detail and explained it all.

After 200km, it looks good. Give it a good blow on the highway, and if it's okay then, it will probably hold up.

Best regards, Rainer.