You are here:

Triumph Repair/TR7 Leaky Water Pump


QUESTION: Hi Howard:

Thanks again for considering my question(s) on the TR7 water pump.

I have conducted the "loose radiator cap test" you suggested in a previous answer.  I ran the car to full operating temperature and then shut it down.  I loosened the cap (I noticed some pressure escaping) and let it sit overnight.  

I checked the car this afternoon and there is no leakage from the slot in the engine block as before.  

I'm assuming that there is a leaking seal in the pump and it will have to be repaired. I must say that I'm not looking forward to repairing this again. It's not a particularly easy job.  Please let me know if you have any other thoughts and such.  


ANSWER: Sometimes the seal will seat in and stop leaking but only some milage on the car will tell.

If you do have to go into it just be sure to polish the surface on the bottom of the impeller so it will have a better seating. I have found some factory impellers and aftermarket impellers with a rough finish on the surface that contacts the seal. Also be sure to clean and put a little sealer around the outter lip of the seal when you install it in the block. The older version had a brass sleve with a "O" ring but I think your car didn't have the brass sleeve. The seal just fit directly into the block.


[an error occurred while processing this directive]---------- FOLLOW-UP ----------

QUESTION: Hi Howard:

Thanks for the advice.

One issue I have observed on currently available pumps is that they come "assembled."  Do you advise separating the components out (removing the brass cage, etc) before installation into the block?  I did this when installing the pump, however removing the brass cage was difficult.  I fear that I may have damaged that seal when I disassembled it.


I have installed them both ways except I would never install a pump with the impeller on the shaft. For the very reason I had mentioned, too many came with a rough surface that the water seal rides on.

When you get a new pump with the impeller installed remove the left hand threaded bolt from the impeller and remove the impeller with a puller, don't try to drive the shaft out of the impeller. This way you can first examine the water seal surface and then you can install the whole pump into the block. But, I found it much better to smooth the inside bore of the block and champher the top edge of the block and I would even polish it with fine grinding wheel with a Dremell tool. First stuff a shop rag in the hole so as to keep out shavings.

The reason I did that was to be able to get the "O" ring of the brass sleve to enter the block without any damage due to the sharp edge left there by the engine manufacture. And smoothing of the bore ensured a better seal when the "O" ring is in it's position.

You have to take great care when installing a preassembled pump because as you force the sleeve down into the block the shaft will sometimes hit the corner of it's bore at the bottom and put a strain on the shaft and this can cause to water seal to pop out of it's position and it just barely sits in the brass sleve. You can't bump down on the shaft itself because there is very thin snap ring on the shaft that will pop out and you won't know it.

I always liked to build the pump in the block myself but as you know most pumps today come assembled but it can be done, but with much care. I round and polish the edge of the block and smooth the block bore where the "O" rings are going to seat and clean out the bottom bearing surface that the shaft fits into. Then I lub the "O" rings and block and carefully insert the whole pump (less the impeller) and I have a piece of thick wall alumminum tubing that just fits the top of the brass sleve that I use as a drift to bump on the brass sleve as the pump goes into the block. The brass itself can't handle much tapping on.

I only bump in a slight bit and then feel the shaft to see that it has some free play in rotation as it enters the bottom bearing and engages the gear teeth. It only moves a little as it is engaging the jack shaft gear but it is enough to know that the shaft is not in a bind or any strain is on the shaft while installing the pump. Just before the brass sleve is all the way down on it's lip I put a little sealant around it's lip. All the time I am bumping lightly on the brass sleve I am feeling the shaft to be sure it is free. So it is a sequence of bump lightly and feel the shaft and bump lightly and feel the sahft, etc.

If you bump down on the brass sleeve and the shaft hits a tooth on the gear or the end of the shaft hits the edge of it's bearing you can dislodge the the bearing in the brass sleeve and the oil seal. If you bump down on the shaft you can easily damage and dislodge the snap ring on the shaft and thus the oil seal. It sounds like a "Catch 22" but it can be done.

When the pumps use to come as a kit I had several hand made tools to assemble the pump in the block. Even in the dealership we didn't have the factory tools so we made our own. Assembling the pump in the block was a sure method to get each part in it's place correctly but I would not disassamble a pump if it came assembled. I just had to take care not to get any part damaged as I installed it. Even the impeller can be troublesome installing after the pump is in. Normally the shaft will try to screw itself down into the block due to the angled gear teeth on the shaft when you tighten the top left hand threaded bolt and if there is a lot of distance below the bearing, it can put a strain on the snap ring so I liked to start the spline of the impeller on the shaft and then hold the impeller while tightening the bolt, thus not putting a strain on that very small snap ring.

Even good mechanics were tripped up by this engine. As it had other strange things that trip up mechanics that tried to work on them. I did learn to like the car and had several of them and still have one. Read my story about one I converted to run on straight Alcohol.

let me know how it turns out.


Triumph Repair

All Answers

Answers by Expert:

Ask Experts


Howard M. Fitzcharles III


Triumph TR-4 up & Spitfire, and Engine theory


Dealership line mechanic on MG, Triumph, Jaguar for 15 years, Instructor in commercial mechanics school 2 yr. Product information manager for piston and valve manufacture, Instructor & hotline answer man for import car parts importer 15 yrs.

Associate member SAE EAA member

Import Car magazine

ASE Master Auto with L-1 certification up to 2000

©2017 All rights reserved.

[an error occurred while processing this directive]