Yet Another Rookie Move

ECROVER

Member
Hoping one of the talented forum members can tell me if if there is a way to determine what type of brake fluid is in the reservoir? The previous owner of my '69 TC2000 told me the vehicle takes Dot 4 or Dot 5 and I added Dot 5 thinking it was a higher number so must be better! Come to find out they are incompatible and can do damage if mixed. Would you necessarily know by brake performance if any damage had been done? What to do know besides find someone capable to take over the car? Thanks for any advice offered.
 
Here ya go
Beginner's Guide: What Is Brake Fluid (and What Do the DOT Numbers Mean)?

If you put DOT 5 in the reservoir and did not pump it round the system by bleeding then use a syringe to suck it out again and clean out the pot. Re fill with DOT 4. As explained in the article 4 and 5 are not compatible.
I use Super DOT 4 as it has the highest dry boiling point of the glycol fluids, it is hard to find sometimes, the best place I have found is at a Ford dealer, but last time I bought even they had to order it in.

If you put in 5 and it got around the system you need to get it out of the reservoir, re fill with DOT 4 and bleed again thoroughly and hope that the seals have not been compromised.
I suspect the damage will be swollen seals and you may find calipers sticking on and a servo issue. In which case every rubber seal on the car will need changing, and if you have a tandem feed reservoir the clutch will need attention too.
You cannot tell by looks what you have in there.
 
This interested me as it is something that you dread happening and I wanted to know if there was a solution apart from a full strip down.

Now you read lots of stuff on the old interweb and a lot of it you have to take with a pinch of salt and conduct proper safe research, especially with safety critical items, so I suggest that also applies to my two posts here.

Mixing the two types of fluid can mean the result is a gel forming in the system. Also the seals may leak.

If all you did was put the fluid in the reservoir as a top up, then suck it out and clean up the pot and put DOT 4 in as stated .

However if you bled it through then you have a choice to make.
Take every item apart and clean and flush through and fit new seals.
Try flushing the system to clean out the mix. This may or may not work as some DOT 5 will linger in tight places. It will depend whether you did a full change to DOT 5, or just added a little.

The flushing agent that will clean the system is denatured alcohol. You need to do your own verification of this, it is NOT my recommendation.
 
I've seen when both types have been put in the same glass container, and over time they separate out, so if the OP has just topped up the reservoir and not pumped it around then I agree with cobraboy, suck it all out from the reservoir and refill with the correct fluid.
 
Here ya go
Beginner's Guide: What Is Brake Fluid (and What Do the DOT Numbers Mean)?

If you put DOT 5 in the reservoir and did not pump it round the system by bleeding then use a syringe to suck it out again and clean out the pot. Re fill with DOT 4. As explained in the article 4 and 5 are not compatible.
I use Super DOT 4 as it has the highest dry boiling point of the glycol fluids, it is hard to find sometimes, the best place I have found is at a Ford dealer, but last time I bought even they had to order it in.

If you put in 5 and it got around the system you need to get it out of the reservoir, re fill with DOT 4 and bleed again thoroughly and hope that the seals have not been compromised.
I suspect the damage will be swollen seals and you may find calipers sticking on and a servo issue. In which case every rubber seal on the car will need changing, and if you have a tandem feed reservoir the clutch will need attention too.
You cannot tell by looks what you have in there.
Thank you both for taking the time to reply to my question. I have not noticed any separation in the reservoir so maybe I lucked out. Your response suggest the need to contact the original owner if possible to see if he remembers what he used. Both your expertise and kindness is appreciated!
 
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