Radiator drain plug question

[Member 10617]

It's the little things that get you! Take a radiator drain plug, for example.

When I had my car in the shop last week for its Spring Tuneup, the mechanic recommended that I have my new (1-year old) aluminum radiator flushed. I thought it was a little early for this, but was told that the machine shop that rebuilt my engine "uses chemicals to clean the block... and also use what they call a pill to seal the freeze plugs." He said that by flushing now and totally eliminating those chemicals, I would be good for three years (possibly even five) before another flush.

But that's preface to my question.

The mechanic who was working on my car set about to drain the radiator. To my surprise, it had an anodized aluminum plug rather than a petcock at the drain. To remove it takes an allen wrench. Unfortunately, when the mechanic tried to remove the plug, it either wouldn't budge or convinced the mechanic that something was wrong and there was a danger of stripping the threads. He said he wanted to leave the plug alone and preferred to drain the radiator through the bottom radiator hose.

He said that I could try to take the plug out and replace it with a solid brass drain, but in his opinion it was better just to make a habit of using the bottom hose to drain. He said, "Petcocks freeze up and break when you try to open them all the time. Most cars today don't have them. Bad things if you do get it out and the threads are messed up. It won't hurt just to leave it (the plug) in"... and drain through the bottom radiator hose.

My question(s) (a) Have any of you ever encountered this situation? (b) What do you think about the recommended course of action?

Draining through the hose is a bit messier, but I'm OK with it, plus it give me an opportunity to check the condition of the hose.

 

[Don Elliott]

The original brass drain taps (the one for the rad has a different thread and part no. than the one for the block) won't rust but they can get gummed up and turn green and I've broken the handle off one trying to open it. They can also leak. When you drain from an original TR radiator by opening any sort of tap you have there, the coolant will splash all over and you will lose most of it on your garage floor. It will also run down the side of the frame of your TR and you will find it dripping off the frame back near where the doors are.

SO DON'T WORRY ABOUT SPLASHING IT FROM THE LOWER END OF THE RAD HOSE. THE PROBLEM THERE IS HOW TO GET IT OFF. YOU'LL FIND THAT IT'S NOT EASY.

 

[Member 10617]

Don. The mechanic who drained my radiator had no trouble taking the radiator hose off, but that's perhaps because it is practically new (put on about 9 moonths ago when the radiator was installed and the engine rebuilt).

Either way -- drain tap or hose -- is messy, as the coolant tends to flow out in many directions. So I guess I can live with that.

My main problem with using the radiator hose (how common is this?) is that inorder to do a thorough flush of the radiator, you hve to go through the filling and draining procedure about 4 or 5 times (drain coolant, two flushes with water, refill with coolant), which means you are constantly taking off and putting on the radiator hose! I'm afraid that such a complication will lead someone to simply DRAIN the radiator, fill it with new coolant, and call it a day -- not a real FLUSH.

 

[TR3driver]

There are drain valves available that have a hose fitting for the outlet. In theory you can add a hose into your bucket, but I find that usually the stream is well defined enough to just put a pan under it.

However, my radiator shop doesn't even bother with the drain valves. Instead they remove both upper and lower hoses (plus the thermostat) and use a machine to force mixed air and water through the system under pressure.

IMO unless it has been neglected, there is no need to go through all that. A well-maintained system won't have any crud to be flushed out; only clean coolant with nearly-exhausted chemicals. Just draining both ends, and refilling with fresh coolant should be adequate. The few ounces of leftover old coolant won't hurt anything.

But that's strictly a theory, as mine always seem to wind up neglected :laugh:

 

[M_Pied_Lourd]

Lex,

If it makes you feel any better, the later TR6's had no drain petcocks installed in the radiators. To drain the rad you would do as suggested and remove the bottom rad hose.

Cheers,
M. Pied Lourd

 

[Member 10617]

Randall and Monsieur Pied Lourd,

Thank you for the reassuring messages.

First: If I drain and refill my radiator once a year, it looks like I don't have to go through all the agony of a full "flush." This is what the people at the shop did this year, the end of the first year for this radiator, and they did not suggest a flush.

The reasons for my draining and refilling once a year are (a) for some it seems to be standard procedure, and (b) I have an aluminum radiator and the folks at the shop say that it is important to refresh the chemicals fairly often: every two years is OK, annually is best.

I didn't know that the TRs had no drain petcocks installed. Perhaps that is what my Triumph friend was talking about when he told me that "most cars" don't have them.

I think I'll avoid possible damage to my radiator by trying to wrestle the drain plug out and stick to just removing the radiator hose.

Once again... many thanks.