Thread: coolant dripping from V8

The problem you had was already there - the citric acid solution did nothing to create an issue, it simply brought it to your attention sooner than later when you thought 'everything was fine'

So long as you performed the flush with the correct proportions, then neutalized tha acid with a clear water flush before adding coolant, your flush procedure will be fine.

Mercedes used this exact process as part of factory service procedure for all their engines, regardless of metal constituency, and a specific coolant for the alloy engines which eliminates scale and slime - i.e. it never occurs.

Most notably, over the past couple of decades, I have witnessed spectacular coolant system failures, resulting in major overhauls, which stems from the longterm use of the incorrect coolant type (in MB case either a green generic coolant or a red coolant which are not to MB spec 325.x)

As engine metallurgy evolves, the coolant types also do same. This is exactly for the issues you have encountered - i.e. corrosion from dissimilar metal contact.

It matters not - not now anyway, as you're obviously going to be in for a major investigation / repair / replacement of major components.

Suggest you use ARP head studs if you're going to pull heads and do gaskets, and also make sure the entire cooling system - including heater matrix and pipes, radiator heat exchangers for oil / transmission are all in perfect serviceable condition, before you re-test the cooling system.

It's always an annoyance and the degree of frustration is usually compounded by the neglect/ignorance/abuse of the previous owners tenure. (or current owners in certain cases)

Hope you find that the damage is minimal.

fwiw, standard MB citric acid flush process is to remove thermostat, flush with clear water, mix 500g anhydrous citric acid to the cooling system water volume (approx 13-15L depending) and bring to operating temp, let circulate for 30 mins, then turn off engine, wait 10-15 min, drain flush with clear water, refill again, run for another 30 mins then drain, flush and only then add the specified coolant in the correct ratio (depending on spec 320.1 datasheet) per the engine type number. in the case of the pre-2000 models it's a 50/50 coolant to water ratio, but some later engines use different coolant types and different ratios.

I have employed the older standard (i.e. period correct matching process and fluids) for my v8 and 300TDI and in the case of the MY92 v8, it was only mildly bad when purchased. It has not developed any corrosion whatsoever since 2014 with only one drain interval in that time (which was instigated by a fan clutch failure, that destroyed the radiator).

the 300TDI I recently purchased is absolutely horrible. I have only drained and flushed it at this point, as the vehicle has only been in my custody for 5 weeks. A baseline needs to be established and an operational profile observed before going full-send on the cooling system.

As you have discovered, the process of correctly flushing the system has resulted in your discovery of an issue that has been there for a significant amount of time. These things take literally years to develop into a problem, and only the harshest of water/coolant abuse leads to premature failure..

for example - my v8 has 400,000km on it and the cooling system on the engine is all-original - including water pump. There is no sign of corrosion, and surprisingly so, when the fan clutch failed some years back, which led to this observation.
The heater matrix has failed about 12 months ago on that vehicle - common failure to age and o-rings. my vehicle was not fitted with the early soldered tank unit unfortunately, but received the plastic tank variety. Useless things they are in that installation.

Anyway, I think you're about to discover that the corrosion is in the head-gasket-water jacket mating face area, or possibly same in the block. Either way, if you are pulling heads off, you'd be wise to invest in an overhaul, unless it can be established (before you pull heads) that your compression is nice and even and high on all cyllinders. any one cyllinder that is down more than 15% from the others and I'm afraid it's all system go on a replacement / rebuild. If rebuilding, then it's time to consider budget and doing things properly versus slapping it all back together.

Stepped liners, new pistons and rings, properly machined block (i.e. properly align bored/squared up and correctly decked) which will cost a penny or ten. Might as well recondition the heads, even for more performance (friend of mine has built quite a few 5.4 stroker high performance engines which give a solid and fuel-efficient 450bhp) but this will mean deeper pockets, as many parts will be replaced. crank, rods, pistons, valves, valve springs porting etc.... lots of work and lots of $$$$.

Ultimately, this is a very very good reason why a donor vehicle makes sense - because you can get replacement engine, trans, electrics, body parts etc, for less than the cost of an engine rebuild, and you can literally do this several times, before it equals the cost of a properly rebuild high performance efficient engine.

I really do not envy you. I have experienced the rover v8 phenomenon known as 'cost-effective-operational-lifespan'

At some point, you're either going to make the decision to cough up the cash up-front and do it all now, or perhaps do this slowly over a longer time period - which ultimately costs a lot more and keeps maintaining the legendary status of "Range rover Reliability" (i.e. lack thereof) due to things always needing doing, because they should have been done much earlier, but for reasons of cost or time or both were not done.

That's just the way it is.... some things will never change.

best of luck regardless of the path you choose.

G`day ,

coolant leaks at either end of the heads can be gasket related and the gasket there can decay over time the coolant runs there .

The water jacket is between the head bolt you mention and the one above , same at the rear .

Sometimes they only leak externally , i would pressure test that cylinder and have a look at the spark plug colour and compare with the one next door .

Check the inlet bolts and associated are tight though the norm is for liquid to show at the rear of the valley and down the back of the block .

You could fill the coolant system pressurise it with air , not a lot as it would be cold and see if you can locate the leak .

Good news is end leak coolant are not usually block faults .

Cheers
Peter

@mercguy, thanks for your long response! Allow me to get into it for a bit:

I did do the flush with the thermostat in place since the P38 has the "sputnik" in the lower hose which can't be removed so there is that. In order to get the temp up I did drive for a short while (15 mins I reckon) at low speed, just enough the get some heat into the engine. The systems contains 12L of water and indeed 500grams of acid. During the drive the hoses got hard and there was no leaking, but once cooled down the fun started.

The funny thing is, or maybe not, this engine has had a complete rebuild (I bought is as such) in late 2017. It had everything done, from crank to cam to heads, all of it by RPI in the UK. I installed a new radiator and pump and what not when I installed the engine and filled it back then with mono-ethylene glycol pre-mixed good for -38 (since I drove to the north cape in winter that was needed). As far as I can tell this is the correct coolant for this engine, I believe they only changed the coolant on the THOR engine and this is still a GEMS. The car (well the engine) has done 75K in the mean time and the coolant was replaced last year. In terms of years this is on the long side, but in terms of use and heat cycles it is not a lot I would think?

This engine, since it was completely rebuild, already has the top hat liners, the plugs look great and so does the inside of the engine since I had it apart (except for taking the heads off) last month due to suspected play on the crank which turned out the be just within spec. New gaskets (including valley) had also been fitted and no signs of coolant leaks were found at that time. Regarding the engine insides, there is next to no residue inside the heads or the block since I change oil every 5000km and flush the engine whilst I am at it. This thing lives a pampered life

I will be pulling the heads and will search for ARP studs. I hope that only the head gasket has failed and not the engine itself because I am not sure if I want to invest in another 9K engine rebuild (that's what this one cost me in 2017 all in.)

How often did you say you flushed the cooling system like this?

@PLR regarding the head studs, it has happened it seems that the later engines were not machined properly and the bolt/jacket could break into each other? I hope that is not the case but we will have to see. At least you give me some hope it is not a block issue here is hoping!

Thanks Guys! I am looking for transport to a mates garage since I no longer have a shed to work in and then I will pull the thing apart, I'll keep you posted!

-P

@prelude ,

The cooling system flush is not required at every service interval, but it is a recommended practice for any of the ferrous metal blocks with alloy heads (older pre-1982 v8's and all inline 6 cyls), but the all-alloy v8 engines also do well with the flush, especially where non-genuine spec coolant has been used.

I bought a 1972 350SLC back in 2008 which had been through several P.O.'s and serviced by a (**expletive list too long to type here) that ruined nearly every drivetrain component. the very first thing I did was flush to factory spec, as when I removed the thermostat housing, it literally crumbled. I hoped the heads were serviceable as I'd thought I had just purchased a boat anchor. The slime and scale buildup from the green coolant was simply not believable without seeing it first hand. for a 45mm coolant passage to be choked down to less than 15mm and full of slimey green-white-brown scale I was very scared. Nonetheless, I flushed the system with citric acid solution, but used a large 20L bucket instead of the radiator - I fabricated a sort of swirl-pot inside the bucket, to spin out all the crap. As the engine came up to operating temperature, the stuff started coming out in chunks and then started to disintegrate in the swirling coolant.

It was at that point I had to stop and re-evaluate. I placed a swimming pool skimmer box sock (filter sock) at the bucket inlet to catch all the crud coming from the engine. I ran the flush for about 40 minutes, but the water was disgusting. I could see the stuff working, but had no idea how much longer I should run it. So I drained it all, flushed with water and started again immediately. Second time, I took a risk and used double strength solution, got the vehicle up to temp and ran it for an hour and a half in the driveway - checking on it about every 10-15 minutes. A horrible thick foam developed on the top of the liquid in the bucket, and I repeatedly skimmed it all off until it subsided, which took just over an hour. I kept running the flush and after another 30 minutes I decided that my confidence was at it's limit. "now or never". As I drained, even more large chunks of stuff came out. bits of rust that would have jammed a water pump impeller on any given day somehow came out the lower hose. So I flushed the remainder out - then pulled the block plugs (on an m116 mercedes this is a very high-risk process, due to them never being used for their intended purpose) and after flushing several times, I put a little camera inside the blocks coolant passages from all the accessible apertures, to find -everything was absolutely spotless - So I flushed everything again, but systematically went around the block drains and one by one ensured they were free flowing and clean, then I re-tapped the block threads and put in new plugs with thread sealant. I replaced the thermostat and it's housing with a new genuine part, THEN I took the radiator to a local earthmoving radiator specialist - who informed me the core was 80% blocked and so I asked them to put a new high efficiency core in. Returned with the new radiator, new hoses and paid through the nose for genuine blue coolant from the MB dealer (couldn't get the lemforder stuff at the time) and refilled.

Up until the time I sold that vehicle, the cooling system was absolutely stable, however, several years later, it did develop a leak at the head gasket - and while I had delayed the engines demise by several years, the new owner was made acutely aware of the issue, and upon their pulling the heads, discovered that the coolant passages were absolutely fine, but the 42 y.o. composite gasket had suffered from the poor cooling due to previous owner maintenance - the rear of the head had warped just enough to let stuff escape, but not fail.

Apologies for that long story - but that was the only instance where something so catastrophically bad was the cause of problems much later down the track where proper serviceing had subsequently extended the lifespan of the mechanical components, only to result in the failure mode that was originally predicted.

I have several MB's and all of them get a flush and new coolant every 5 years. Genuine hoses seem to last about 15-20 years, whereas aftermarket OEM will only comfortaably do between 5-8 years. Same for the genuine alloy radiators, where the OEM Behr-Hella or nissens units will fail in as little as 2 years due to pathetic o-ring sealing on the end tanks.

Regardless, I have routinely flushed all of the cooling systems on all my vehicles regardless of brand, with the prescribed MB process, and used the blue lemforder coolant on all the ferrous block / alloy head engines as well as the all-alloy engines. In every single case, not a single bit of scale, corrosion, slime or detritus can be found in any of the engines. The 300TDI in the RRC I purchased 5 weeks ago is yet to undergo the "treatment" and it's cooling system is properly feral. It looks like it has had hard water and no coolant in it for years. Nonetheless, it will recover quite well I feel.

The only caveat I place on the process, is that regardless of the claimed lifespan of the coolant, it does lose it's efficiency quite noticeably after about 2 years. Even if the stuff will last 5-8 years as bottles claim, that is only if the citric acid flush is performed properly prior to refill with fresh solution. It does not cover a simple drain/replace maintenance activity. (imo this should never ever be considered as a coolant system service).

So, in your case, I am leaning to an issue which RPI should probably cover under a gentlemans agreement, with regards to the 'fit for purpose' implied guarantee.

No way in hell should these things overheat - and in the case of my old MY92 v8, as I have previously explained - one flush - brand new looking internals afterwards and zero cooling system issues caused by coolant. Only the failed fan and the catastrophic radiator damage - not related to the actual cooling system, but a mechanical failure of the fan retaining ring on the fan clutch.

I feel like I have to make some kind of blanket statement for the Rover v8's along the lines of - only a terribly maintained engine with extreme high mileage and in the poorest of condition, should give cause to cooling 'issues'.

Anything else - especially oon a well-maintained vehicle, requires investigation and in the investigative process, it's more than likely to observe that a failure is due to defective replacement part used. Whether that's genuine or OEM or aftermarket - only the investigation will reveal.

Before you pull the heads, do a cooling system gas check (tee-kay head check) and observe if there are combusion gases in the cooling system before you pull heads. Rover V8's (as noted by Peter earlier in this thread) have a unique ability to deliver head gasket failures in cooling passage to external, or 'cylinder to cylinder gas exchange program'. and rarely does a coolant passage fail to combustion chamber and 'steam clean' the cyliinders and heads - those are usually from repeated excessive overheating resulting in slipped liners and that's seemingly more common on the serpentine belt motors than the earlier ones (no specific evidence to support, but anecdotally it would appear to be the case). I have no idea why and no evidence to support that statement, but many others have observed similar.

Because of your location, I'd sit down and do my sums on the cost to rectify said issue before plunging in. I'm pretty sure that a company such as RPI would only use quality VRS kits and composite head gaskets from Elring or Reinz - I wouldn't think they'd use mls head gaskets unless they could absolutely guarantee longevity. Nothing wrong with the mls gaskets, but they are of variable quality depending on manufacturer. Also, mls gaskets are less forgiving of poorly matched surfaces, so if there is a bit of warpage in the block or heads or the liners aren't perfect, you may discover your issue lays there. Sometimes it's literally a 'suck it and see' exercise, and best intentions are not always the best outcome.

regardless, I'm sure that a careful observation when pulling it down will reveal a couple of potential causes.

best of luck, hope it's not serious.

I like the merc stories Forwarded them to a friend of mine who owns several (and is currently putting a straight 6 in a G wagon)

Well, I had to move the car (and a 2 tonne range rover does not move on muscle power on anything but smooth tarmac) so I filled the cooling system up to drive 15meters to get the car level on hardened surface where I could work on it. The (distilled) water was really pouring out and I decided to remove the alternator and bracket to see what is what. Turns out, the freeze plug in the cylinder head has sprung a leak!

IMG_6635.jpg

I guess I am glad it is fairly reachable and is probably not an expensive fix, it just makes me feel: is this a one off thing, a bad plug to begin with (since it seems to like just fine) or is there more going on. I send RPI a mail and have checked the interwebs and core plug sets are readily available and not that expensive to obtain in any case.

Now to find instructions as to how to do the job

Cheers,
-P

G`day ,

10 bolt heads have one either end , the one opposite the plug sits in a different shaped pad , the threaded hole is further away , same as what is on the front of the other head .

Putting the rear one in could be done by making a small press using bolt , nuts etc .

Getting it out maybe make a small puller with something threaded into the plug (depending how rotten it is ) sort of idea .

They go in easily if done squarely , coming out what ever works .

If you don`t want to raise/take the engine out or heads and heads it would be off , some lateral thinking will be required .

Contacted RPI and they will send me new ones free of charge. Now to "just" replace the bugger

-P

True to their word I received a couple of new plugs and I set out to remove the old ones. It was quite the challenge and I did scuff the aluminium somewhat. Hopefully the new plug will seal properly but only time will tell. Worst case scenario I will have to cut thread in the hole and use a plug that can be screwed in but lets hope it won't come to that.

Cheers,
-P