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MG TD TF 1500 - How does coolant get into crankcase?

A couple of months back I reinstalled my Arnolt heater with a semi-Arnolt adapter designed by Declan. I did some 'clever' measuring of the coolant going back in so as to get a look at the 14.4 pint refill. I've hardly driven Lazarus since then. But, I seem to be needing to top up the radiator. I've stopped convincing myself that it's just the heater doing it.

Looking at the dipstick I'm beginning to suspect that the reading is a little bit higher than I normally expect to see it to be. What is the most likely spot for coolant to be getting into the crankcase. I can think on no engine events since then, except for that stretch when my rear carburetor was taking a break.

Is there something I'm likely of screwed up in reinstalling the thermostat/housing when I did the heater? Gauge indications and engine sounds seem to quite normal. Thanks for any hints. Bud
Bud Krueger

Bud after the engine is cold loosen the oil drain plug just enough to have a few drops leak out. IF there is water in the oil the water will drip out first.
Also IF there is water in the oil the dip stickand or the oil filler cap will look like Mayonnaise.
A trick to refilling the coolant, with no air trapped is to install the thermostat with a asprin holding the thermostat open.
Safety Faster!
Len
Len Fanelli

besides the head gasket the only place is the rear cylinder head water cover plate.
There is a plugged drill way supplying the rocker feed. Original gaskets had a segment which covered this in case of leakage. The cover plate is also pressed out to compress the gasket.
Are you sure it is a loss and not just the normal expansion of coolant. I have had friends complain of fluid loss and when they stopped topping up, the level stabilised.
Ray TF 2884
Ray Lee

i top off my radiator all the time. the cooling system is not pressurized, so is essentially open to the air and so evaporates quickly when engine is fully warmed up. especially when driven a lot.

so ya, i'm doing something i hate on forums...not answering and then questioning the question (sort of)...my apologies.
hh hoolihan

The coolant level should be no highter than 1 3/4" below the ovweflow pipe!
Len Fanelli

Bud,
If you fit an expansion tank. You can fill the rad to the top and it will stay totally full. Giving you more volume of water in the system and you won't have to top it up so often. As what gets pushed out through expansion, gets pulled back in as the system is leak free and Atmos pressure will move the coolant back into the radiator. Down in Florida Once I have filled the system and marked the bottle with a full mark when hot and another when cold. I could monitor how much would evaporate. The system is open to atmospheric pressure, but the tube is 3/8"OS dia. The expansion tank does not get that hot.
IN a year I only had to add one inch of mixed coolant to the 1/2pint expansion tank to keep it at the full mark when engine was hot not an arduous chore as it is in the battery box. Overflow does not seem to have ever been used.
Just a thought.
Rod


Rod Jones

Hi Rod, see http://www.ttalk.info/Tech/Overflow_tank.htm. I've had a coolant overflow recovery tank since 2004. That's why I'm trying to figure out why I'm having to add coolant. There's no sign of leakage under the car. Almost has to be getting into the crankcase. Thermostat area is the only place disrupted in the past couple of months.
Bud
Bud Krueger

A cracked cylinder head or leaking head gasket can allow coolant to be expelled through the exhaust when the engine is running. Pull the valve cover and look for condensation or mayonnaise. A loose plug behind the rear cover plate will more likely cause oil to contaminate the cooling system as the oil is under pressure where the coolant isn’t. Again mayonnaise or oil will be seen in the coolant. A porous cylinder wall or loose sleeve may also be a cause
W A Chasser

There is a simple and cheap tester you can purchase at any auto parts store that will check your coolant for combustion gasses. If it is a head or head gasket, there will be gasses in the coolant.

Google combustion leak tester.

Bruce Cunha

Thanks, guys. It's got me puzzled. There was no such drop in coolant before I did the heater plumbing a few months ago. There is no sign of any leakage under the car. No mayonnaise signs. I'll try cracking the crankcase plug later today to if any water shows up. I topped up a couple days ago and it has dropped a couple of inches since then without having started the engine.
Thanks, again.

Bud
Bud Krueger

To hh, you fill up your radiator all the time??? I drive mine all summer, thousands of miles, 100F temps at times and need to add maybe twice a Summer. If you top it off it will puke out what it doesn’t need and will maintain that level. You should only back fill to that lower level.

Regards, Tom
tm peterson

Huey, are you sure you aren't overfilling? As others note, you can't fill it to the top because when the coolant gets hot and expands, plus the pressure from the pump, it will spill out until it finds its level. I rarely add coolant to my TC.

Bud, if the coolant is getting past the head gasket then you should be able to see evidence in the combustion chamber. One or two clean pistons and the others dirty is a good sign of water getting in. Or if the car has been sitting a while, there will often be moisture or liquid in there.
Steve Simmons

The two times I’ve seen water in the crankcase there was no question about it.

The oil turns the color of coffee with cream and looks like mayonnaise. And it doesn’t take very much water.
G D

Bud,

Further to Steve's comment about coolant getting past the head gasket and into an adjacent combustion chamber, here's another possibility:-

If the piston for that chamber happens to have 'parked' near the top of the cylinder and the associated exhaust valve was still slightly open, coolant seeping into the chamber could make its way out through to the exhaust manifold, down the exhaust pipe and collect at the low point of the pipe where it curves back towards the muffler, or even into the muffler.

Was this coolant loss measured in the header tank or overflow tank? To me, two inches of fluid loss would be a substantial amount which could support this suggestion.

It would be interesting to see what blows out of the exhaust pipe at the moment you start the engine (if you haven't already done so)?

David
David Padgett

David, you may have hit it! A couple of months ago I went through a strange series where my rear carburetor was being ineffective. At that time I was getting a significant amount of carbon blowing out of the exhaust pipe. I had to put a sheet of plastic down to protect my newly paved driveway at the garage. I was blaming it on too rich a setting of the carburetors. I had also newly installed heater plumbing heater. Unfortunately, we're having a cold spell with nighttime temperatures in the low 30'sF and an unheated garage in the low 50's. Looks like some disassembly work is on the docket. Thanks, David.

Bud
Bud Krueger

Bud
If you take the sparkplugs out and let it sit for a couple of days then hold a sheet of paper/cardboard accross the plug holes and get someone to give it a crank over--If there's any coolant in a cylinder it should show up on the paper-
willy
William Revit

In cold temperatures, a bit of moisture and black stuff isn't uncommon. When the hot exhaust cools, water condenses in the exhaust pipes. When you first fire up the car with tehe choke on, it's running very rich which makes the driveway spotting issue worse.
Steve Simmons

I concur with Steve's assessment regarding cold temperature start-up. Mine spits out sooty water droplets on initial cold start-up with the choke on. Knowing this, I usually drape a shop towel over the rear bumper hanging down far enough to cover the exhaust pipe to catch it. After a few minutes that stops, and further warm starts with no choke don't do that. Even on modern fuel injected cars with ECM's they will still produce water droplets (less the soot) at the tailpipe on start-up. Those usually have weep holes as well in the muffler/resonator to address moisture accumulation. I've never had any issue with the radiator fluid level dropping unless I filled it to the top. It spits out what it does not need and stabilizes about 1 inch or so below the top of the radiator. As such, I would not use exhaust moisture as a viable indicator of a water leak.
Jim Rice

To test head gasket leak between chamber and coolant, try to inflate the cylinder with an adapter :
https://www.manomano.fr/p/bgs-technic-adaptateur-dair-comprime-cylindre-m14-et-m18-34262182.
Head gasket is damaged if you hear bubles in the coolant circuit.

Laurent.
LC Laurent31

Les, the few drops that came out look like oil. Trying to eek out enough to see some separation resulted in a tub full of oil.

How tall would a tube of motor oil have to be to see a separation of water at its bottom?

I've ordered an analyzer to see if there's exhaust in the coolant. Expect it tomorrow.

Should have temperatures in the low 60's tomorrow so should be able to work in the garage and will remove the heater system. Anybody have a suggestion for a really good sealant for coolant components?

I've had a coolant recovery tank in operation since 2004. I've seldom had to add any coolant. That which was pushed out of the overflow tube was sucked back in later. http://www.ttalk.info/Tech/Overflow_tank.htm.

I just hope that it's resolved by Christmas so that Santa can do his usual roll through Marietta in a TD.

Bud

Bud Krueger

Bud:

I'd recommend Loctite 545. I use this to seal the threads around the water temp bulb in the thermostat housing (TF). The housing threads were a bit corroded/pitted/worn after all these years. Coated the threads with this stuff and no leaks. Worked like a charm.

Jim


Jim Rice

Bud,

My thinking was that if there was a substantial amount of coolant accumulating in the exhaust system, at cold start-up, there would be lot more than the usual few droplets of moisture being blown out the back!

As you said, you hadn't started the engine since topping up the coolant, and then noting that it had dropped in level after a couple of days.
So, if it ain't in the crankcase and it's not on the floor, what other options are there???

If you still haven't started up yet, I'd support William's comment about removing the spark plugs and inspecting inside.

David
David Padgett

Just a thought--or two
Firstly ,because you now have extra coolant with the addition of a heater and hoses, the coolant level will most likely rise further with temp and drop further as it cools just because of the increased capacity of the cooling system
Second , Seeing this only started with the addition of a heater--maybe the heater itself is leaking inside the car---or not-?
William Revit

WR may be on the right track. Can you shut off the coolant to the heater(both inlet and outlet) to see if there is still a coolant loss? Maybe the problem is the plumbing to the heater or the heater itself.

Just musing.

Jud
J K Chapin

Maybe you had some latent trapped air in the heater and plumbing? I have had a couple cars that required turning the heat on and topping off a couple times after draining coolant. My TD had leaking headgasket, and the oil was milky white. My 280Z would fill a cylinder with coolant overnight and I would have to pull the plug and spin it over to pump coolant out before starting. Yes I was a broke student and it was during finals, but it kept me going for a few weeks! You can pull the plugs, rotate until pistons TDC and look in the plug hole with a good light. If leaking into a cylinder it will look totally different, maybe with all the carbon gone. Or let stand for a day and you may see coolant. George
George Butz III

George Butz, It's lucky you caught that on your 280Z as many decades ago, I worked on a TD that had hydro-locked and it bent a connecting rod, just enough, to touch the bottom of the cylinder wall creating a strange ticking noise when running.
John Quilter (TD8986)

Hi there. Story to be so quite on this lately. My garage is unheated and we are in the midst of a cold spell here in Georgia. At the moment the outdoor temperature is 31.3°F, garage temperature is 46.2°F. Spent much of yesterday with cold 53° hands. So what's new?

There is no mayonnaise anywhere to be found in Lazarus' engine. The engine oil analyzer that I was convinced to buy is for looking for exhaust indications, not water. Another $40 spent. Removed the recently installed (Declan-styled) heater plumbing. Discovered that the screw threads in my thermostat housing elbow are 10-32. (http://www.ttalk.info/modern_thermostat.htm). Have gone back to OEM cooling plumbing, except for thermostat-related.

Where I don't have mayonnaise, I may have foam. A few months ago when, installing the heater, I needed a one gallon contain into which to drain coolant. Nearest thing I had was an almost-empty jug of wooden-floor cleaner. I emptied the jug and carefully rinsed it out a few times before draining coolant into it. Noticed some foam on top of the liquid in the jug. Thought nothing about it. That foam appears to have survived two bouts of Prestone Max Cooling System Cleaner. Shortly I will be flushing the engine with white vinegar to get rid of any foam-causers in the system. Then I'll hit it with the Prestone Max again before filling with distilled water. (followed by Prestone).
BTW, I did find a possible leak at the thermostat housing to water outlet. Anybody know of a good, modern or old style, goo to put on coolant gaskets? Bud (waiting for the garage to get over 50°F)
Bud Krueger

I use Right Stuff to seal cooling system gaskets when needed. I've never had a failure even on pressurized systems. There is a chance however, that the elbow is heavily corroded. Might want to check that and replace it if necessary.
Steve Simmons

I've used Permatex #2 (non-hardening) for decades. Never had a problem using that stuff with gaskets.
Jim Rice

Like Jim, I prefer a non-hardening and non-RTV gasket 'dressing'. Hylomar blue is safe with and resistant to pretty much all automotive fluids.

https://hylomar.com/en/universal-blue/
M Hyde

Permatex Ultra Grey -- Best stuff going, resistant to coolants-oils

willy
William Revit

Right Stuff is by Permatex and is non-hardening, non-RTV. I haven't found anything it doesn't work on. I've also used the others mentioned with good results, but personally prefer Right Stuff. The only downside is that it may be a bit harder to remove, but still comes off with a razor blade pretty easily. It's also really good for filling imperfections on sealing surfaces. Temp rating I think is around 450F, and you can return the part to service immediately after assembly.
Steve Simmons

This thread was discussed between 06/12/2023 and 12/12/2023

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