Can I just bypass my 85 300D aux water pump? Its leaking...

[Carrameow]

Can I just bypass my 85 300D aux water pump with a Union until my new one comes next week? Its leaking...I still would like to use the Car however--will this cause overheating?

[Pete Burton]

yes, and it wouldn't cause overheating, but why not wait for the part and do the job once? My thinking here is that subjecting the hoses to 2 procedures instead of 1 increases chances of tearing, as those hoses are likely original like mine. Plus, it's extra work, and I try harder and harder now to do a job just once.

[Luke]

Mine happens to be seeping now too - started I guess about a month ago. I have ordered a replacement, but in the mean time I am driving it. It seeps what appears about a few table spoons a day at the pump-half seam. Keep an eye on your temp, and fluid level. I make a 60 mile round trip commute run every day, so far I have only had to replenish about two cups of fluid in that time. 'Hope my new one will be here tonight. Unless yours is really squirting you'll be ok. And I fully agree with Pete - don't fondle those hoses more than you need to.

If I were you guys, I would disconnect the electrical connector from the aux pump while waiting for the new part. Once the aux pump draws more than 1.3 amps it can and often will fry the climate control unit. If it is bad enough that it is leaking, there is a good possibility that it is crudded up enough to be drawing too much current.

Good luck and Merry Christmas,

[Luke]

Thanks for that, Larry. I'll pull the plug before heading home tonight.

[Jimmy Joe]

I am scrounging for parts for the bypass today, and sending off payment to a kind member here who has a replacement aux pump.
I will post pics of my progress.
One question I have though, is why does the servo fry if the aux pump goes? I have heard it over and over....
That servo is a shame, I sure would like to figure out how to replace it entirely with a manual system.

[Old300D]

Originally Posted by Jimmy Joe

I am scrounging for parts for the bypass today, and sending off payment to a kind member here who has a replacement aux pump.
I will post pics of my progress.
One question I have though, is why does the servo fry if the aux pump goes? I have heard it over and over....
That servo is a shame, I sure would like to figure out how to replace it entirely with a manual system.

A DC motor will draw a lot of current when it stalls. This excess current will fry many motor drivers, including, I expect the CC servo.

[rwthomas1]

It is very simple to add a relay to power the Aux pump direct from the battery/buss bar. Use the CC to switch the relay and install a quenching/suppression diode to prevent inductive kickback from the relay itself. Go here http://www.bcae1.com/ and do a search on relays and it will tell you how to do it. RT

Well, here I go again, skimming the question before formulating my answer. When I saw that it was Carrameow posing the question, I thought it was his '87 124 chassis car. My answer was based on the 124 system, not the earlier cars.

Putting a relay to drive the pump and picking the relay with the wire that now runs the pump is a good idea.

Merry Christmas,

[Jimmy Joe]

Originally Posted by Pete Burton

... subjecting the hoses to 2 procedures instead of 1 increases chances of tearing, as those hoses are likely original like mine.

Yikes, if the hoses are close to tearing I would argue that it is time to replace them. Those are tough little hoses, if you can tear them by twisting em off the connectors, they are gone, and gonna blow on you....better tearing in your hand than on the freeway.

I just bypassed by servo and aux pump completely, and created a loop for the coolant to flow.
Might be crude, but I got heat again!
I will take pics and post the botch job...