1G Quick question on replacement vacuum hoses

[XC92]

Some of the vacuum hoses on my Talon are looking a bit worse for wear and it would probably be a good idea to replace them. I got a loaner vacuum test kit from Autozone that I intend to use to see if there are any leaks, plus I got a stethoscope to double check everything. But even if it all checks out I think it would be good preventive maintenance. I'm just wondering what kind of hose to get.

I actually just bought some from RockAuto since they were pretty cheap, around $0.50 a foot, and I was about to order some other parts and it didn't increase the shipping, figuring that I could use them for something else if they're not good enough to use as vacuum hoses. I got several sizes, 4mm, 5.6mm & 6.4mm (they're all SAE so I had to approximate).

They're all Gates, and seem pretty thick-walled and strong. Are those OK, or should I get the RTM kit, which warns to stay away from cheap and flimsy hose. But these don't seem flimsy, even though they are fairly cheap. The car's stock, so stock intake pressure and vacuum levels, if that matters.

Btw, stupid question, but why do these cars use vacuum so much to control things? Why didn't they use solenoids and motors? Would that have been too expensive back then, or the technology to use those wasn't as developed as it it today? Do modern cars still mostly use vacuum actuators, or do they tend to use electric ones? Just seems so pre-21st century (which of course these cars are).

 

[steve]

1G's have 5 things controlled by pressure;
Fuel Pressure - track manifold pressure to normalize injectors (Electrically varied for warm starts)
Wastegate - Pressure activated (Electrically varied)
Blow Off Valve - Differential Pressure (there is an internal port in addition to external)
Exhaust Gas Recirculation - Coolant Temp and Vacuum
Fuel Vapor Purge - How vacuum works here confuses me (Electrically varied)

 

[SilverSpyder98]

I have a 2G so I'm sure I have less vacuum hoses than you do, but I still do have a few. What I've noticed is that some hoses are higher quality than others particularly the evaporation system ones. Others (like the one from the intake manifold to the pvc valve) are the standard ones like what you probably got and what you can get at any parts store. Good quality rubber, but not so heat resistant and they become hard with age especially if they run in a hot area over or next to the block and start to leak at the connections. The ones on the evaporation system on my car however are some kind of maybe heat resistant silicone that so far I haven't seen replacements for but despite the car being 24 years old, they are in perfect condition. If you could find hose of that material, I'd replace my hoses with that. My strategy has been to only replace the hoses that are old and hardened because the replacements will go the same route in a relatively short time. But replacing old hoses did solve some pesky little performance issues I had like when the engine had been running a long time on hot days, I had engine speed issues at low vehicle speed and low gears slowing down and stopping and starting up again like when you come to a traffic light.

As to your question about why they used vacuum control back in the day, I think it was a technology evolution thing. When emission control first came out, electrical systems in cars were pretty primitive and engineers used vacuum control because it was something simple they could rely on. But then as emissions controls tightened, the maze of vacuum tubes increased until under the hood it looked like a bowl of spaghetti and reliability suffered. It was time consuming to track down all those potential vacuum leak areas, so they gradually moved to electrical controls.

 

[XC92]

Yeah, I have the same idling or low speed issues when the engine's warmed up. Not sure if it's vacuum leaks, clogged fuel line or injectors or something else, but I'm basically going to strip everything down, clean it all, and replace everything that should be replaced, gaskets, o-rings, heat-cycling fasteners, hoses, etc. I'm even going to drop and clean the tank and pump and replace all the hoses there, and see if the pump needs to be replaced. I want the engine purring after I'm done, not barking or coughing!

And yeah, I'm starting to understand the role of vacuum hoses in cars from the 80's & 90's and how it's being replaced by electronic actuators, which wasn't possible at this price point back then. It's kind of Rube Goldberg but it was probably the best way to do this back then (although I don't understand why the wastegate solenoid doesn't directly control the wastegate valve instead of via vacuum since it's so close to it). Plus I understand that it also serves the purpose of relieving intake vacuum pressure under certain conditions, but I'm still fuzzy on that. I can't believe how much I'm learning about how cars work!

 

[SilverSpyder98]

A PCV valve can cause those issues as well so I checked that first. Easy thing to do. Just jiggle it to see if the valve is stuck and if it is a replacement is cheap. That was okay, but then I noticed the hose that ran from the PCV valve to the intake manifold was kind of loose at the connections and the hose was really hard. I also had a similar condition hose that ran from the rubber intake tube between the intake filter and the manifold to something I can't remember (maybe the EGR valve or something like that). So I replaced both of those hoses and removing those air leaks fixed that same long standing issue with my car and now it runs perfectly at low speed and high engine temps. Anytime you let outside air come in where its not expected and in greater quantities than expected you mess up the air fuel ratio as the ECU tries to compensate. So I learned a lesson that I always need to remember to check the small things first. There could be other issues of course, but I would bet once you get all your vacuum hoses replaced that aren't so hot, your similar performance issues will go away as well. Start simple and dig deeper if needed.

With cars this old (as long as you don't inherit a car that someone really messed around with that didn't know what they were doing) it seems you can trace a lot of issues back to simple things like deteriorated rubber things or sticky electrical connections in areas where car manufactures skimp on the quality of the connector types. Like most of the electrical connectors are high quality modern types but on connections that aren't considered as critical, they used some really basic old fashioned types of connectors that are prone to corrosion. For instance I had the engine temp gauge stop working and all it was was a simple push on brass connector to the gauge temp sensor on the block that got corroded. A little polishing of the connector and the gauge worked again. Same with the oil pressure sensor. Same kind of connector had gotten damaged from being bumped too many times and set the oil pressure light on the dash to blinking as car movement jiggled the connection. Thought I had an oil pressure issue and that was all it was! And you see that with all cars. Most stuff is pretty durable, but they have their weak points where they tried to keep costs down.

 

[XC92]

I replaced the PCV valve last year with an OEM but perhaps the hose has a leak. But I'm going to inspect everything and replace anything that leaks or looks like it needs to be replaced. I'm going to be really methodical about this and basically overhaul the entire fuel, intake, exhaust and turbo systems. After 30 years it just seems like the right thing to do.

1G's have 5 things controlled by pressure;
Fuel Pressure - track manifold pressure to normalize injectors (Electrically varied for warm starts)
Wastegate - Pressure activated (Electrically varied)
Blow Off Valve - Differential Pressure (there is an internal port in addition to external)
Exhaust Gas Recirculation - Coolant Temp and Vacuum
Fuel Vapor Purge - How vacuum works here confuses me (Electrically varied)

Do you know if standard Gates thick-walled vacuum hose is ok for turbo cars, or should I really go with silicone? Everything is still stock, ~200HP.

 

[pauleyman]

Do you know if standard Gates thick-walled vacuum hose is ok for turbo cars, or should I really go with silicone? Everything is still stock, ~200HP.

there is nothing special about the vacuum lines that I've found. I've been using off the shelf whatever they have at the parts store for 20 years. The only issue I could see if the stock lines are kinda thin so the small spring clamps the factory uses with those would probably work better with the thin hose. Not even sure it's necessary for most things.

 

[XC92]

I got some extra Dorman spring clamps just in case, and if not there's always local auto stores as they're not that expensive. I assume that I can even use worm gear clamps as I have a bunch of those lying around. But the Gates hoses seem pretty sturdy and thick.

Still kind of amused that even as recently as 20-30 years ago they were using pneumatic tubes to actuate various engine add-on parts. Seems so clunky and primitive even if I get the rationale. But then I look at the turbo wastegate actuator with the long rod and actuator "bell" that looks like a kid's bike bell and think what genius thought up that Rube Goldberg setup.

 

[XC92]

Does any anyone know how many T-fittings I'll need for all these hoses, and of what sizes? So far I found 2x4mms, but perhaps there are others?

Also, where do I buy the various intake hoses? I mean the big ones, not the vacuum ones. Some are starting to crack. There are 3 that connect to the intercooler, 1 to the throttle, 1 from the air box to turbo, and 1 from the bypass valve to the air box-turbo hose. OEM is pretty expensive, assuming they're even still in production. Are these generic parts I can get from auto stores?

 

[steve]

Depending on how much is going back stock There are 2 T's, 2 funny 3 port connectors on the EGR, and an interesting three port on the Purge.

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