# Seal swelling or stop leak for leaky hydraulic clutch cylinder? **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** chevrolet, s-10\ **Created:** [October 20, 2025, 2:38pm UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284 "2025-10-20T14:38:04Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![cwatkin](https://avatars.discourse-cdn.com/v4/letter/c/59ef9b/32.png) [@cwatkin](https://community.cartalk.com/u/cwatkin)\ **Post date:** [October 20, 2025, 2:38pm UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/1 "2025-10-20T14:38:04Z")
As mentioned in an unrelated thread, the clutch cylinder is leaking on my 2000 S10 4.3L. This is one of those things that can be managed by carrying a bottle of brake fluid and topping off when needed. I am debating about keeping this truck long term so wasn’t wanting to spend $1000 to have the entire clutch replaced. Unfortunately the cylinder is in the bell housing so the engine and transmission have to come apart and at that time you just replace the entire clutch set. This seems to be more of a problem in cooler temps. Is there any kind of product that could slow down or stop this for a bit? I know it would be a band-aid but figure it might help in the short term while I decide if I want to keep the truck. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [October 20, 2025, 2:50pm UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/2 "2025-10-20T14:50:29Z")
You cant use a stop-leak product on a hydraulic system. Too much pressure produced. The leaking hydraulic component will require rebuild /replacement. Tester ---
**Author:** ![asemaster](https://avatars.discourse-cdn.com/v4/letter/a/5f9b8f/32.png) [@asemaster](https://community.cartalk.com/u/asemaster)\ **Post date:** [October 20, 2025, 5:39pm UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/3 "2025-10-20T17:39:14Z")
> [@cwatkin](#): > > engine and transmission have to come apart and at that time you just replace the entire clutch set. Well, you don’t **HAVE** to. Are you doing the work yourself? If so, then there’s nothing stopping you from removing the trans and inspecting the clutch disc. If there’s plenty of meat left on the clutch plate and the pressure plate/flywheel don’t show much wear, you can just replace the hydraulic cylinder and put it back together. Money-wise you would only be out the cost of the cylinder and some fluids. Of course a retail shop that is expected to provide a warranty on the job wouldn’t do this… ---
**Author:** ![cwatkin](https://avatars.discourse-cdn.com/v4/letter/c/59ef9b/32.png) [@cwatkin](https://community.cartalk.com/u/cwatkin)\ **Post date:** [October 21, 2025, 12:40am UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/4 "2025-10-21T00:40:19Z")
Yeah, I would have a shop do it. Most of the cost is labor. Clutch sets are not that expensive, all things considered. If it has to come apart, I would do the entire thing, otherwise I might see how long I can kick the can down the road and do nothing major. I am sure the clutch disc is probably not in terrible shape but why reuse something like this? I would just get the clutch set with the cylinders and bearings included and do the entire thing. I wonder if part of the issue is this truck sat quite a while and the seals dried out from lack of use. ---
**Author:** ![cwatkin](https://avatars.discourse-cdn.com/v4/letter/c/59ef9b/32.png) [@cwatkin](https://community.cartalk.com/u/cwatkin)\ **Post date:** [October 21, 2025, 12:42am UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/5 "2025-10-21T00:42:50Z")
I had to get new tires on this during the time I had to call it back into service due to a mechanical failure of another truck and weather total of another car. Maybe run it to keep miles off some of my others and see where I stand once the tires are worn out. Either way, I won’t sell it for $500 with basically brand new tires on it. I would run it for a bit to keep miles off my newer stuff and decide once the tires are done for or something major goes wrong. If I put close to $1000 into a clutch set and install, I would be more likely to hang onto it a while longer of course. ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [October 21, 2025, 2:20am UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/6 "2025-10-21T02:20:14Z")
You seem to be certain the clutch slave cylinder is leaking and not the clutch master cylinder. Did you see a leak? ---
**Author:** ![oldnotdeadyet](https://avatars.discourse-cdn.com/v4/letter/o/a6a055/32.png) [@oldnotdeadyet](https://community.cartalk.com/u/oldnotdeadyet)\ **Post date:** [October 21, 2025, 11:24am UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/7 "2025-10-21T11:24:44Z")
I learned the hard way that my Mazda B2300 had located the slave cylinder inside the bell housing. All my previous cars had external slave cylinders you could replace yourself for $20. My question is: why in the world would you ever locate an item that needs frequent replacement inside the bell housing? I have now put that on my list of cars I would never buy. ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [October 21, 2025, 12:15pm UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/8 "2025-10-21T12:15:16Z")
Your B2300 was a rebadged Ford Ranger, most of the big 3 have/had the slave cylinders in the bell housing, and they normally last the life of the clutch, whereas the most of the (Asian) imports run external slaves… I have replaced way more external slaves due to failures alone then internal slaves due to internals for whatever reason (too early to think lol), internal are normally just replaced with the clutch kits… ---
**Author:** ![jtsanders](https://avatars.discourse-cdn.com/v4/letter/j/c2a13f/32.png) [@jtsanders](https://community.cartalk.com/u/jtsanders)\ **Post date:** [October 21, 2025, 12:37pm UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/9 "2025-10-21T12:37:36Z")
> [@cwatkin](#): > > temps. Is there any kind of product that could slow down or stop this for a bit? Stop leak liquids that swell seals should always be considered short term solutions. They swell the seals. Swelling is the first step in dissolving the seals. It will work for a while but eventually the seals will break down even more. These products should be used only to delay replacement. I know this isn’t an issue in this case, but IMO it’s worth noting for future reference. ---
**Author:** ![cwatkin](https://avatars.discourse-cdn.com/v4/letter/c/59ef9b/32.png) [@cwatkin](https://community.cartalk.com/u/cwatkin)\ **Post date:** [October 21, 2025, 4:45pm UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/10 "2025-10-21T16:45:55Z")
I will verify which cylinder this is. If the master, that will be an easy fix. This happened once before and it was the slave. The behavior and need to add fluid was the same but it might be a different failure. I know the shop I use likes replacing both cylinders as a set. They say that the new cylinder will overpower the older worn unit, causing it to leak shortly afterwards. If it is the master that is leaking, I am willing to do this on the cheap and take that risk, especially since I don’t know if I plan to keep this truck long-term. I will verify where the leak is before using any type of seal softeners because that make it so that both cylinders would need replacement. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [October 21, 2025, 4:55pm UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/11 "2025-10-21T16:55:57Z")
Pull the carpet back from the fire wall and see if fluid is running down behind the carpet from the master cylinder. Tester ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [October 21, 2025, 9:24pm UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/12 "2025-10-21T21:24:37Z")
> [@cwatkin](#): > > I will verify which cylinder this is. You should have done that before considering a clutch replacement. > [@cwatkin](#): > > They say that the new cylinder will overpower the older worn unit, causing it to leak shortly afterwards. Hillbilly reasoning, the hydraulic pressure will not increase with one new cylinder. ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [October 21, 2025, 10:14pm UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/13 "2025-10-21T22:14:07Z")
> [@cwatkin](#): > > They say that the new cylinder will overpower the older worn unit, causing it to leak shortly afterwards. What can happen is when the clutch (brake) fluid breaks down and gets contaminated with corrosion and whatnot, it starts to damage the seals, pistons and bores and that same fluid is shared between the master and slave cylinders, so when one fails the other might not be far behind… I have replaced one and have the other fail soon afterwards, just like calipers and wheel cylinders, therefor it is best to replace them in sets, now with the internal slave, if I replaced it due to a failure, I replace the master also, but if I only replace it due to a clutch failure then I don’t replace the master, but I will replace the master by itself due to the expense of replacing the internal slave… If it is an external slave, then I replace both no matter which one fails as a rule of thumb… ---
**Author:** ![JoeMario](https://avatars.discourse-cdn.com/v4/letter/j/3bc359/32.png) [@JoeMario](https://community.cartalk.com/u/JoeMario)\ **Post date:** [October 21, 2025, 10:41pm UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/14 "2025-10-21T22:41:37Z")
There was a comment earlier about maybe not replacing the clutch disc if the internal slave cylinder was replaced. When an internal slave cylinder leaks, how often does it soak the clutch disc with fluid? ---
**Author:** ![cwatkin](https://avatars.discourse-cdn.com/v4/letter/c/59ef9b/32.png) [@cwatkin](https://community.cartalk.com/u/cwatkin)\ **Post date:** [October 22, 2025, 1:25am UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/15 "2025-10-22T01:25:56Z")
The clutch seems fine but has over 100,000 miles on it. I wouldn’t reuse it no matter what. If I pay for the labor to tear the engine and trans apart, then I will pay an extra $200 for an entire clutch set. ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [October 22, 2025, 3:08am UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/16 "2025-10-22T03:08:35Z")
> [@oldnotdeadyet](#): > > My question is: why in the world would you ever locate an item that needs frequent replacement inside the bell housing? Frequent replacement? The clutch release bearing/slave cylinder assembly eliminates the need for a clutch fork. I don’t consider the clutch fork to be an engineering marvel, people will complain if they hear a squeak within the clutch system. ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [October 22, 2025, 4:40pm UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/17 "2025-10-22T16:40:15Z")
> [@cwatkin](#): > > If I pay for the labor to tear the engine and trans apart, You are making it sound like a major overhaul, it only pays 5.5 labor hours to R&R the flywheel, a good shop if replacing the flywheel and not waiting on a machine shop to resurface it, can do the job by lunch time same day if nothing goes wrong, not that hard of a job… But I agree, if the trans comes out and the clutch has miles on it, it will be replaced… as well as a one piece rear main seal… ---
**Author:** ![asemaster](https://avatars.discourse-cdn.com/v4/letter/a/5f9b8f/32.png) [@asemaster](https://community.cartalk.com/u/asemaster)\ **Post date:** [October 22, 2025, 7:02pm UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/18 "2025-10-22T19:02:47Z")
> [@davesmopar](#): > > as well as a one piece rear main seal… You mean there were rear main seals that were 2-pieces? 😀 Next you’re going to tell me that people used a piece of rope stuffed around the crankshaft to keep oil in the engine. ---
**Author:** ![oldnotdeadyet](https://avatars.discourse-cdn.com/v4/letter/o/a6a055/32.png) [@oldnotdeadyet](https://community.cartalk.com/u/oldnotdeadyet)\ **Post date:** [October 22, 2025, 8:55pm UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/19 "2025-10-22T20:55:14Z")
My slave cylinder replacement frequency has been on Japanese cars of the 80’s and 90’s, and I probably changed two per car in 200K miles. The B2300/Ranger needed one replacement at 150K and probably cost $800, partially because I replaced the clutch that did not need it while in there. The $800 was retail while the $20 slaves were DIY. Confession: my 2007 Mazda 3 with 210K has never needed a slave, and I have no idea where it is located. ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [October 22, 2025, 9:43pm UTC](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284/20 "2025-10-22T21:43:48Z")
> [@oldnotdeadyet](#): > > Confession: my 2007 Mazda 3 with 210K has never needed a slave, and I have no idea where it is located. Like your other JDM’s, it is externally mounted and only pays 0.7 labor hours… [Next page](https://community.cartalk.com/t/seal-swelling-or-stop-leak-for-leaky-hydraulic-clutch-cylinder/204284.md?page=2)