MB 1120 Coming to America! Purchase, Build and Now Travel!

[Sitec]

So I have pretty much decided to remove the cylinder head with hopes that the head gasket will be the source of our coolant loss problem.

Hi Jon. Have you put a pressure tester on the coolant system when it's cold? If not, it's worth parking the vehicle on a dry clean flat surface and then pressurising the system with a rad tester. If the pressure does not hold steady, then the water is going somewhere, or the tester/cap is leaking. A squirty bottle full of soapy water sprayed lightly around the cap will find any air leaks. It's important to carry out this test when the engine is cold, as small leaks will show up as drips. If you do it when the engine is warm, these small leaks will often evaporate before the water hits the floor, thus eliminating the chance of finding the leak... Once you have the system holding decent working pressure, now is the time to crawl all over the engine with a head torch on. The water will glisten in the light!

If the outer edge of the head gasket has failed, then by pressure testing the system when cold, there will be a visible leak between the head and the block, or the oil in the sump will have gone milky (over time and use). However, if the head gasket fails on the inner edges, then water can (rarely) be consumed by the engine, but usually the combustion pressure is more than the coolant pressure, so the coolant system gets over pressurised by combustion pressure. There is a test for this available... A coolant sample can be sent for analysis, and they'll tell you if combustion gasses are present in the coolant.

How much coolant are you loosing, and over how long? Are we talking pints per day or pints per months? The reason I ask this is because if you have the head gasket replaced, and the truck still looses coolant, you're going to be out of pocket and at a loss... Time spent now diagnosing is often time well spent.

 

[luthj]

Adding a dose of UV dye and a bit of waiting has paid me dividends previously.

 

[VerMonsterRV]

Hi Jon. Have you put a pressure tester on the coolant system when it's cold? If not, it's worth parking the vehicle on a dry clean flat surface and then pressurising the system with a rad tester. If the pressure does not hold steady, then the water is going somewhere, or the tester/cap is leaking. A squirty bottle full of soapy water sprayed lightly around the cap will find any air leaks. It's important to carry out this test when the engine is cold, as small leaks will show up as drips. If you do it when the engine is warm, these small leaks will often evaporate before the water hits the floor, thus eliminating the chance of finding the leak... Once you have the system holding decent working pressure, now is the time to crawl all over the engine with a head torch on. The water will glisten in the light!

If the outer edge of the head gasket has failed, then by pressure testing the system when cold, there will be a visible leak between the head and the block, or the oil in the sump will have gone milky (over time and use). However, if the head gasket fails on the inner edges, then water can (rarely) be consumed by the engine, but usually the combustion pressure is more than the coolant pressure, so the coolant system gets over pressurized by combustion pressure. There is a test for this available... A coolant sample can be sent for analysis, and they'll tell you if combustion gasses are present in the coolant.

How much coolant are you loosing, and over how long? Are we talking pints per day or pints per months? The reason I ask this is because if you have the head gasket replaced, and the truck still looses coolant, you're going to be out of pocket and at a loss... Time spent now diagnosing is often time well spent.

We have pressure checked the engine once while hot. The radiator leaked so I replaced that. Have not done the test again. We are losing about 4 liters every 50 miles and do have white smoke now. With that amount of coolant loss I still see no external leaks. At this point we have had 3 different mechanics look over the engine, the first ones spent about an hour doing it and found nothing. Problem then arises as they are not willing to open up the engine, just were hoping to find an external problem. We need to drive the truck about 1.5 miles to the mechanic's shop. I will ask them to check things out before they start the destruction.

I have been told about if it leaks into the combustion chamber it will over pressurize the coolant system. Occasionally we do notice a coolant odor while driving but still do not see the external leak. One mechanic felt the head would be cracked near an exhaust port, but we needed to open it up to find out. On the German LN2 forum I am a member of another member has been very helpful, he is a retired MB mechanic of 35 years and said he has never seen or heard of a MB with a cracked head (wish he lived close by). Have also been told (by mechanic #2) that the exhaust gas coolant checks are not very reliable, that most older engines will show positive. Unfortunately I am no mechanic so am relying on others experience with anything internal. If we were not living in the truck and parked in a place we could be a while I would give the work a try. The WIS gives some pretty detailed instructions on the removal/install process. I am hoping 2 days in the shop and our problem will be solved, and at the very minimum figured out.

 

[Sitec]

With 4 litres every 50 miles, it does indeed now should like it is consuming the water. That said, you mentioned you can occasionally smell coolant which tells me there is still an external system leak... I'd assume the mechanic that is doing the job will carry out all the normal diagnostic tests prior to doing the head gasket. Keep us updated.

 

[VerMonsterRV]

Yup, I plan to ask him to do his own diag before he starts tearing into it. The gasket kit is there if it is needed. Best case scenario he finds something we have missed and is an easy fix, if not open it up and see what we find. If it is just the gaskets then I will be happy, hopefully not something a bit more drastic (I have a very vivid imagination ). I try and plan ahead as well as possible, I know of a furnace welder if the head is cracked and also a potential replacement engine. Hope all of that is not needed. Will hopefully have an update tomorrow evening.

 

[Madoxen]

Fingurs crossed for the best result and not a nasty supprise.

 

[Neil]

Good luck. You will be glad to get to bottom of this, its been spoiling your enjoyment for too long.

Neil

 

[VerMonsterRV]

Quick update. The head is off. Once the valve cover was removed there was sludge (coolant+oil) on the valve rockers. The head gasket looks ok and so far no visible cracks in the head. We are sending the head off to get it magnafluxed. The mechanic has turned the engine over and the cylinder walls look good. The o-rings in the injector sleeves do look old and dry but no major faults in them. So far no smoking gun on where the coolant is going, we are up to about 1 gallon per 50 miles, so it is going quick. We are definitely noticing white smoke but still can not see how it is getting into the combustion chamber. Since the mechanic found evidence of coolant in the oil (never saw it during oil changes or on the dipstick) at the valve cover he is recommending replacing the main and rod bearings. Luckily Expedition Imports in CA had those items in stock and are over nighting them to us. Still wish we knew the source of the leak.

 

[wfv56]

Makes you wonder about a cracked block if the cylinder head passes inspection.

 

[VerMonsterRV]

Makes you wonder about a cracked block if the cylinder head passes inspection.

The mechanic had looked into the cylinders and they look good. No sign of am external leak on the block.

 

[Madoxen]

I realy hope you get the answers and an easy stress free fix. Can only imagine how frustraiting this is seeing the problem but not the reason or solution

 

[luthj]

It might be a little late now, but an oil analysis can tell you if you have bearing damage, and what level of coolant contamination there is. Surprisingly main bearings can tolerate a significant amount of water in some cases. Though sliding surfaces like pistons skirts and cams are less tolerant.

 

[VerMonsterRV]

Yup, a little late. The bearings are out and show some wear. The crank looks good. The new bearings are arriving today so reassembly will start. The mechanic has just started to clean up the injector sleeves and has found one with pitting. This might be our problem. If so it will be great to get it resolved but a very expensive o-ring. Sort of surprised that the integrity of the oil/coolant system relies on an o-ring inside the head.

 

[VerMonsterRV]

It might be a little late now, but an oil analysis can tell you if you have bearing damage, and what level of coolant contamination there is. Surprisingly main bearings can tolerate a significant amount of water in some cases. Though sliding surfaces like pistons skirts and cams are less tolerant.

The mechanic has taken a look at the cam and all looks ok. Unfortunately the "bearing set" showed up and instead of a set it is a single bearing. Mix up at the place I bought them from and they are working on it now. Now we see 3 out of the 6 injector sleeves are pitted. So new ones will be installed (hopefully they have 6 of them at the place we are getting the bearings from). Mechanic now is thinking these sleeves were our problem. Luckily the rest of the engine looks good, though we are still waiting for the word on the head being magnafluxed.

 

[Sitec]

The plot thickens... So, as your mechanic has prob pointed out, sludge in the rocker cover (looks a bit like partially cooked egg white) is a good sign there is an internal water leak. Fingers crossed it is the injector sleeves. Having the head crack and pressure tested will hopefully also eliminate that too. There are a few other things worth checking while the sump is off... Are the piston bores in your engine block just part of the block, or does the engine have liners. If it has liners, there are two types. Wet liners and dry liners. Dry liners don't tend to give much trouble, but occasionally wet liners can weep coolant out of the bottom where there is an O Ring between the block and liner... (picture a bigger version of your injector sleeve, just with a piston in it!). The mechanic should be able to look at them and see if you have wet liners. One last thing... There's no oil cooler on the engine or in the radiator is there? Sometimes if there is an oil cooler built into the engine these can corrode on the coolant side if the vehicle has been run with water in the cooling system instead of coolant... As coolant pressure can often be higher than oil pressure water/coolant will be forced into the oil via a faulty/rusted oil cooler... Just things to consider while you have your engine apart. Keep us posted, and snap a few pics if you can.