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MG MGB Technical - Cooling system tuneup

I've got an 18V engine in good condition out for a transplant to a solid body. Plan to replace clutch, water pump, timing chain, and head, as well as generally clean the sludge off.

This engine has always run a little on the hot side, but has good oil pressure and good performance. I'm not planning to dissassemble the bottom end, but is there anything I can/should do to clean sediment etc out of the cooling or oil passages in the block while it's out?

Thanks
Steve
Steve Aichele

Steve: I replaced a leaking freeze plug ( the rearmost on the side of the block) on my 69 two years ago and when I removed it I found a lot of rust and debris packed in behind it. I cleaned this out as best I could with a stiff wire i.e a bent clothes hanger. If you are a brave soul you might consider replacing a few, or all of these. Read the archives first however. Some people have reported problems with the proper installation of new ones. Most important to use no silicone sealer.
As regards the oil ways I would prefer an engine oil flushing and oil change to digging around in oil ways. Consider replacing the oil cooler as it can sludge up over time.
Andy Blackley

Steve. Were it I, I would take apart the bottom end to see what I had. This requires a lower gasket kit, but it also allows you to replace the rear main seal (order seperately, not included in the Rover gasket kit) which may be leaking by now. It also allows you to replace the main and rod bearings. When my daughter's 77 B engine was first rebuilt, the crankshaft showed little, if any, wear and did not have to be turned. The bearings, however, both rod and main, showed a significant degree of wear.

In addition to the rod and main bearings, I have found, on two of the three engines I have rebuilt recently, significant wear on the camshafts. Some of the lobes show quite signifcant wear to the point where they are not functioning properly (at least in relation to the other lobes). Thus, I would take the opportunity to remove and inspect the camshaft and replace the timing chain and tensioner. When I rebuild, I replace the simplex timing chain and gears with the earlier duplex chain and gears. I am not sure this really matters, but wear on the chain and tensioner do.

I have always removed the main oil galley plugs at the front and rear of the engine and cleaned the passages using a rifle cleaning rod and bore brushes as per John Twist's recommendations. (I prefer to use a .410 shotgun cleaning rod and a .410 bore brush, but I am a shooter and John is not.) At that point, you can either replace the five brass plugs you have removed with original factory style plugs or with brass pipe fittings. E-mail me if you need the procedures to ream and tap for the plumbing plugs. I have used these on my last three engines and they work quite well.

As to the cooling system, Peter Burgess recommends cleaning the cooling system passages with something like CLR. This requires you make up one plug, on the water pump, and flush the system throughly after cleaning.

As to freeze plugs (core plugs/welsh plugs), I use the Rover brand plugs, with a little hard setting Form A Gasket, and have had no problems with them coming out or leaking. Les
Les Bengtson

Steve ,
Have a look at here under pointer . They explain exactly howd to replace welsh plugs onto engine block.
Kind regards .
http://www.octarine-services.fsnet.co.uk/
RENOUG

"replace welsh plugs"

Actually 'welch' plugs, you get leeks with 'welsh' plugs.
Paul Hunt

As well as pregnant sheep ;-)
Paul K

Steve-
Take the car to a competent radiator shop and have the components of the entire system, including the engine, radiator, and heater core, flushed and descaled to remove the 20+ years accumulation of muck, rust, and mineral deposits which act as insulators that keep heat from being dispelled by the cooling system. You'll be surprised at how much cooler the engine will run in the summer and how much warmer the heater is in the winter. Install a coolant pump with the earlier cast iron body as it has the more efficient die cast impeller which has less of a tendency to produce cavitation at high engine speeds, the resultant air bubbles possibly collecting in one location within the cooling passages of the system. Do not use silicone-based Permatex blue RTV sealant on any of the engine gaskets as it is prone to failure under hot operating conditions. Instead, use Permatex Aviation Form-A-Gasket sealant. Make sure that the system is refilled with a mixture of a good ten year antifreeze and distilled water. Why distilled water? Because it won't coat the interior of your cooling system with mineral scale. Why the more expensive ten-year antifreeze? Because it has special additives that will extend the life of your water pump and because you don't really want to do all this all over again next year, do you? You don't have to take this extra step, of course. When your cooling system fails due to a lack of proper care, you can always send Moss Motors $229.95 for a new radiator and $94.95 for a new water pump, plus shipping.
Should the power output of your engine be so great that it overwhelms your cooling system, have your local radiator shop recore your radiator with an aluminum core fully 1" thicker than standard (it will still fit without further modifications) and insist upon the highest number of fins per inch available. The L-type core offered by Modine is excellent for this purpose. They have a website at http://www.modine.com/ . Relocating the oil cooler to a new position behind the front valance will provide unobstructed airflow to the radiator while mounting the vented front valance from the 1972-1974 1/2 models will in turn provide adequate airflow to the cooler.
Beware of cheap radiator hoses. Due to poor wall strength, they can collapse at high pump speeds and restrict the coolant flow to the coolant pump, resulting in overheating. A quality Kevlar reinforced hose (available from Victoria British) should not compress or distort any more than is necessary for mounting. Because these hoses have very little flex to them, they can transmit vibration to the neck mounts of the radiator, resulting in some cases in cracking of the base of the neck mounts. It would be wise to have a radiator shop reinforce these by brazing on flanged sleeves at their bases.
When a localized hot spot forms, it causes the surrounding metal in the head and block to expand excessively. This, in turn, can crush and damage gaskets, causing leakage. Hot spots also create added stress in the head and block itself, which may cause warpage and/or cracking. One of the most common causes of localized hot spots is air pockets in the cooling system. These can form when the cooling system is being refilled or when other engine repairs are being made (valve job, replacing a water pump, etc.). As coolant enters the engine, the thermostat often blocks the venting of air from the engine leaving air trapped in the upper portion of the block and/or heads. Some thermostats have a small bleed hole to prevent this from happening, but many do not. If the trapped air isn't removed, it will create localized hot spots and steam pockets when the engine reaches operating temperature, causing the engine to overheat. A symptom of air trapped in the cooling system would be little or no heat output from the heater when the engine is warm.
Refilling the cooling system so that there will be a reduced likelihood of air pockets is easy once you know how: First, fill the radiator and block by pouring the coolant in through the thermostat housing and refit its outlet cover, then disconnect the heater hose where it connects to the forward part of the pipe that runs along the top of the rocker cover. Insert a small funnel into the hose. Holding the hose above the height of the heater box, pour in the coolant until it flows out of the pipe from the rocker box, then remove funnel and reconnect the hose to the pipe. This will minimize the amount of air in the system. If your car is equipped with an overflow tank, fill it 2/3 full and check it when the engine cools off after breaking in the camshaft.
Of course, water outlet elbow gasket leaks develop over time as the gasket deteriorates from both heat and its constant contact with coolant, in time becoming a real nuisance, not to mention making a mess on the front of the engine. Fortunately, the engineers at Fel-Pro have come up with a solution called the PermaDryPlus® Water Outlet Gasket. Originally developed to deal with leakage-prone warped or corroded thermostat housing flanges, they're constructed of high temperature resistant, edge-molded silicone rubber on a rigid carrier, providing a superior fit, as well as both high heat and pressure resistance. The rigid carrier prevents over-torquing, while the molded rubber assures a secure seal. This part is available from Fel-Pro (Fel-Pro Part# 35562T). Because the studs that secure the thermostat housing to the block project downwards into the water jacket, it would be prudent to install studs made of stainless steel in order to prevent their seizure due to electrolytic corrosion and to coat their threads with a flexible sealer such as Fel-Pro Gray Bolt Prep. These studs are made by ARP and are available from Advanced Performance Technology (APT & ARP Part# THS-1).

Steve S.

Paul ,
Sorry for the mistake . Next time... I check after typing .
kind regards .
Renoug

Here is one additional action you might want to take if you ever decide to pull the engine for a rebuild. After having the block hot tanked, take a leather mallet and tap all around the block (top, sides, bottom and interior). Then use cleaning brushes (per Les' suggestion) and really work on getting all the casting sand out of the block. Repeat until no more crud comes out.

The mechanic that helped me rebuild my engine recommended that we do this and we pulled out half a jelly jar of casting sand. The unfortunate fact is that MG did not exercize very good quality control on block casting and flushing will not remove the casting sand left in place.

The other thing is to make sure that you have the fan shroud in place. This helps greatly in making sure that the fan is pullin air through the radiator and not from around the engine.
Ron Kluwe

Paul Hunt, you deserve to be boiled in sheep fat for that pun :).

I just re-read the post and got the leeks reference.

Ron Kluwe

This thread was discussed between 16/02/2004 and 20/02/2004

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