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Discussion Starter #1 (Edited)
My '95 S4S is at a service centre for a C-service and the mechanic (experienced with Esprits) is having an issue with the brakes after a brake system flush. Apparently the caliper on the front right hand side is not operating for reasons unknown (caliper pistons are operational) - car pulls left. He has flushed the system and gotten all the old fluid out. On the master cylinder there are 2 bleeder nipples one of which will squirt fluid under pressure but the other one will only dribble fluid. Has anyone experienced a non-functioning front brake caliper or have ideas why this is happening?

Many thanks!
 

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Discussion Starter #3
Thanks Travis. If only it were that simple. My mechanic says there is little to no fluid pressure to the offending caliper though.
 

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If you are getting fluid out of one of the bleeder nipples and not the other on the same wheel either the pipe connecting the other side of the caliper is plugged up or the bleeder nipple is plugged up. Your mechanic should be pulling that caliper off and taking it apart to figure out what is wrong with it. Of course the car will pull to one side if one side's caliper is not fully functioning. This has nothing to do with ABS although if you have a Tech 1 it makes the bleeding process easier.
 

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The OP said the problem was with one of the bleed nipples on the master cylinder not the caliper.

When bleeding the two nipples at the master cylinder the ignition needs to be on (engine off). Is that how he was bleeding them?

To verify if the problem is in the master cylinder, loosen the brake fluid pipe nut for the right front brake at the MC a couple of turns while applying a little pedal pressure and it should piss fluid. If it does, then the problem is in the line or the caliper as David mentioned. Be sure to tighten the nut back before releasing the pedal to prevent sucking air into the MC.

Do that check with both front brake lines to confirm they are both working equally.

If it is the MC, maybe following the complete bleed procedure in manual may help as Travis said but if not, MC is probably shot.

I have experienced the same problem with a rear brake on an S4s and it turned out that the line was plugged due to deterioration of the lining itself inside the brake line.
 

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I have experienced the same problem with a rear brake on an S4s and it turned out that the line was plugged due to deterioration of the lining itself inside the brake line.
^^ Not unheard of these days, even on non-Lotus vehicles.

JAE sells nice sets of stainless steel brake lines... -poke-
 

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The OP said the problem was with one of the bleed nipples on the master cylinder not the caliper.

When bleeding the two nipples at the master cylinder the ignition needs to be on (engine off). Is that how he was bleeding them?

To verify if the problem is in the master cylinder, loosen the brake fluid pipe nut for the right front brake at the MC a couple of turns while applying a little pedal pressure and it should piss fluid. If it does, then the problem is in the line or the caliper as David mentioned. Be sure to tighten the nut back before releasing the pedal to prevent sucking air into the MC.

Do that check with both front brake lines to confirm they are both working equally.

If it is the MC, maybe following the complete bleed procedure in manual may help as Travis said but if not, MC is probably shot.

I have experienced the same problem with a rear brake on an S4s and it turned out that the line was plugged due to deterioration of the lining itself inside the brake line.
Missed the part about the master cylinder. If you can't get the master bled you can try bleeding it on the bench. If that doesn't work it may need to be rebuilt.
David Teitelbaum
 

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Discussion Starter #9 (Edited)
Thank you gents for all the fantastic advice. At long last my mechanic was able to rectify the problem. Turns out to be a stuck (brake?) solenoid. He interchanged solenoids and the problem moved to the opposite caliper on the front. Using brake fluid as a cleaner, a fashioned electrical harness to apply power, and compressed air (plus plenty of patience) he managed to get the unit "unstuck" and the front brakes are functional once again (phew!) Now I know what it is like to be an expectant dad.

Many thanks to one and all!!!!

p.s...........

On a separate note when he took the car for a test drive, he noted some odd creaking from the passenger side of the car. When he worked at a Lotus dealership customers would complain of a similar noise. After much investigation turns out the body bolts (behind the seats) may become slightly loose causing creaking or chassis thump at its worse. A simple remedy was to place large washers under the bolt heads (if I understood correctly) and tighten down to displace the gripping power/firm things up.
 

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Glad to hear he got the brakes working, good work on his part!

On the body bolts on your S4s, just adding a washer won't solve the problem. The brackets have a welded sleeve on them that goes through the plywood bulkhead and once the plywood has compressed enough, the sleeve has to be shortened.

Procedure is to cut a flap access hole in carpet behind the seats large enough to get to the brackets and remove them, cut 1/4" - 3/8" off the sleeve, re-install bracket and tighten nuts in engine bay, re-glue carpet.

I think there is a write-up on it somewhere, maybe LEW, but don't have time to look at the moment.

Cheers,
Jim
 

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p.s...........

On a separate note when he took the car for a test drive, he noted some odd creaking from the passenger side of the car. When he worked at a Lotus dealership customers would complain of a similar noise. After much investigation turns out the body bolts (behind the seats) may become slightly loose causing creaking or chassis thump at its worse. A simple remedy was to place large washers under the bolt heads (if I understood correctly) and tighten down to displace the gripping power/firm things up.
Bulkhead Mounting Plate Modification
 
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