Oil in coolant - head gasket?

Engine Oily Bits, Ignition, Fuelling, Cooling, Exhaust, etc.
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Llessur
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Oil in coolant - head gasket?

#1 Post by Llessur » Sun Jan 20, 2019 10:13 am

This morning I started flushing the cooling system on my 1977 2500S - on draining the system the coolant was brown and seemed to be a bit oily (it had a sheen on top of it and left brown sludgy/oily tide marks on the side of the pan I was draining it in to).

Aside from the slight possibility that a careless previous owner accidentally put oil in the radiator instead of the oil filler cap, I presume this points to head gasket failure. From what I've read on the forum this seems fairly rare on the mk2s so before I pull the head I just wanted to double check that I'm not missing any other possibilities.

I have no other signs of head gasket failure - no white smoke/steam from the exhaust, no water or mayonnaise in the oil, no sweet smell to the oil. I haven't got a compression tester but the engine runs quite sweetly and isn't particularly down on power.

If I end up changing the gasket am I right in thinking I have a non-recessed block? The engine is originally from a PI - engine number MG18663HEBW, head number is 219021.
Last edited by Llessur on Sun Jan 20, 2019 9:23 pm, edited 2 times in total.
Adelaide, South Australia (ex-Brighton, UK)
1977 2500S - White

My 2500 blog: https://triumph2500blog.wordpress.com/

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Alec
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Re: Oil in coolant - head gasket?

#2 Post by Alec » Sun Jan 20, 2019 3:22 pm

Hello llessur,

personally if it's running well enough and as you say there are no other signs then I would run it and keep an eye on the oil and water. Although not a major job to change a head gasket it would seem a pity if you remove the head and find no problem?

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Re: Oil in coolant - head gasket?

#3 Post by johnnydog » Sun Jan 20, 2019 8:45 pm

In the past when I have drained old coolant that has been in a Triumph that has been laid up for a long time, and has lost its corrosion inhibitors and/or has been excessively diluted over the years, invariably it is a yukky brown colour and does tend to have an oily sheen to it. New antifreeze does also have an oily texture and greasy feel to it.
Without other confirmation, I would be tempted run it with some type of flushing solution, and then flush it through again numerous times before topping with a 50/50 mixture of coolant /water (add 1/2 the recommended amount of antifreeze and then top it up with water, rather than adding previously diluted antifreeze, as there will be always an amount of 'clean' water left in the system after flushing).
For the cost of a few litres of antifreeze, I would run it for while after flushing and see if the coolant deteriorates noticably - far cheaper and simpler than changing the head gasket at this point!
Incidentally, have you done a compression test?
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1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
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1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
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Re: Oil in coolant - head gasket?

#4 Post by Llessur » Sun Jan 20, 2019 9:30 pm

Cheers for the replies - I was also leaning towards leaving it in the short term and monitoring the situation, especially as I have a classic car show I'd like to attend on 10th Feb which doesn't leave a huge amount of time to get the parts and get the job done.

The sludge that I'm getting out of the system is a weird consistency - not silty like I've had in most cars before, it definitely appears to be more sludgy and oily than that. But then again it doesn't stink of engine oil, and the water in the top of the radiator (yep just water, not much in the way of coolant as far as I could tell) only had a very light oily rainbow on top of it so perhaps it is just sludge and I'm worrying over nothing.

I've given the system a really good flush, backwards and forwards, next job is to replace all of the hoses and refill with coolant. I'm in South Australia so there's not much need for actual antifreeze here, most coolants sold are pre-mixed but I have some left over from another car so I think what I'll do is refill the system, use the car for a few weeks and then, providing there's no other signs of head gasket failure I'll add in some flushing solution and drain/flush/refill the system again for the longer term.

I haven't run a compression test on the engine yet but I'll see if I can pick up a tester and find out what's going on in there.
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1977 2500S - White

My 2500 blog: https://triumph2500blog.wordpress.com/

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Re: Oil in coolant - head gasket?

#5 Post by tony » Mon Jan 21, 2019 1:23 am

I wouldn't run it without some form of corrosion inhibitor/antifreeze even for a short time. We don't need it over here also but I 've seen some horrible messes in cooling systems that have run on straight water. :oops:
Tony.
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Re: Oil in coolant - head gasket?

#6 Post by Llessur » Mon Jan 21, 2019 1:26 am

I always use coolant but sadly the previous owner wasn't quite so fussy... :?

Hopefully things aren't too corroded in there, I'm not sure how long it's been in this state but time will tell...
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Re: Oil in coolant - head gasket?

#7 Post by Jonathan Lewis » Mon Jan 21, 2019 12:14 pm

Just one thought - years back, I understand that some people used to advocate the use of a light soluble oil (e.g. machine cutting oil) as an anti-corrosion additive in engine cooling systems where operating conditions did not require the regular use of anti-freeze. Is there any possibility that a previous owner has done this and the oily residue you are seeing in the coolant is the result thereof?

In terms of going forward, I would tend to agree with the advice already given by previous respondents to this thread.

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Re: Oil in coolant - head gasket?

#8 Post by Clifford Pope » Mon Jan 21, 2019 1:18 pm

Is there only one passageway for oil under pressure from the block to the head, at the rear by the rocker pedestal?
Any other point would just be where return oil at crankcase pressure dribbles down the pushrod holes?

As I understand the oil circulation routes, oil feed to the top of the engine is tapped from from the rear main crankshaft bearing, via a flat on the shaft that passes oil up the supply passageway once per revolution. It is therefore at greatly reduced pressure. Does that pressure actually exceed that of the cooling system? Or is there in fact little net pressure differential making leakage unlikely?

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Re: Oil in coolant - head gasket?

#9 Post by Llessur » Sun Feb 03, 2019 11:53 pm

Interestingly, I found the below on the underside of my bonnet:

Image

According to Google it's a "film–forming corrosion inhibitor and scale suppressant" meant for diesel machinery cooling systems. I wonder if this explains the weird, slightly oily nature of the coolant I drained from my engine?
Adelaide, South Australia (ex-Brighton, UK)
1977 2500S - White

My 2500 blog: https://triumph2500blog.wordpress.com/

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Re: Oil in coolant - head gasket?

#10 Post by harvey » Mon Feb 04, 2019 12:27 pm

Jonathan Lewis wrote:
Mon Jan 21, 2019 12:14 pm
Just one thought - years back, I understand that some people used to advocate the use of a light soluble oil (e.g. machine cutting oil) as an anti-corrosion additive in engine cooling systems
And brake fluid. Just a small amount works as a corrosion inhibitor, and can be used in conjuction with antifreeze.
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