'88 3SFE engine: no vacuum ANYWHERE!

Your engine is running excessively rich and choking everything with carbon. What's the maintenance like on this car? Timing belt, plugs, gaskets, EGR valve cleaning, etc?

Are you getting power brake boost? If so your engine is generating vacuum, just not getting to the small ports. If you clean the P-E-R ports (I mean run a wire and see it physically come through) and still not get any vacuum then you have a serious leak somewhere. I'd think you'll get low vacuum, but NO vacuum? Check all gaskets, cam/crank seals, etc for inexpensive starters.

ger> Its an '88 Camry with 4 cyl. 3SFE engine. I have been trying to figure

The vacuum ports on the throttle body are separate. They port vacuum at different degrees of throttle opening. If you just changed the timing belt, double check to make certain the valve timing is correct. If you're one tooth off, you could be losing vacuum.

Yes, the E and R port vacuums are proportional to the throttle opening and they control the EGR modulator. You'll get increasing vacuum readings at first the E and then the R port with throttle plate opening up to full engine vacuum.

But there should always be full engine vacuum at the P port, as well as the brake booster port, or the PCV hose.

Daniel wrote:

There are varying levels of vacuum, dependent from where in the intake system the vac is being sourced from. Manifold or below the throttle-valve vac is the highest. The brake-booster uses maximum vac from the here. Other parts of the engine use lessor vacuum and may give you the wrong impression if its not registering on a gauge designed to indicate max-vac.

Engine vacuum is highest during run-down from high revs (throttle-valve shut) and at idle. During wide open throttle (WOT) eg during accelerating, vacuum takes a big dive and is the reason the power-brakes has a resevoir incorporated into its diaphragm chamber. It also means you need a one-way valve in the booster vac-line to the booster to stop stored vac from bleeding back into the intake during low vac engine operation.

If the brake-booster has a ruptured diaphragm, the engine will run rough and power assist will be reduced. In this case you can usually hear a hissing sound inside the cabin, coming from the power booster.

If your brakes work fine (the brake pedal should fall slightly after engine start), its not likely there is a severe vac loss problem, but all the same, you need to check all the small vac hoses for splitting etc

The PCV valve can cause engine performance problems if it is stuck open. Test it by plugging the PCV line temporarily at the end which accesses the cam-cover. Apart from that, you maybe looking at ignition or fuel pressure problems. Is the air-cleaner OK?

Jason

Air filter is new. I took off the throttle body and used Berryman B12 and shop air on the P-E-R ports. Now that the engine is back together, I realized there is a capped port on the back side of the manifold, just made for tests. So I checked it there at idle and it is

20 in. vac. So I then checked the P vac. by connecting the gauge up to the P line where it attaches to the temp. controlled vacuum switch. As it should be, there is 20 in vac there also. And that switch is switching the vacuum on when the engine gets up to temp. That vac switch is for the evaporative canister I think. The E port very slowliy goes from zero to about 5 in. as engine is revved. I believe that particular port is very restrictive, unlike the P port...hopefully it is supposed to be! The R port goes from about 0 to 10 in. quickly as the engine is revved. With the fuel press controller vac line connected, I have only about 37 psi on the fuel line between the engine and the fuel filter at idle. As a test to see if the fuel press controller was doing anything at all, I pulled the vac line off, and RPM increased a bit. The fuel pressure gauge went from 37 toi 45 psi. So with the vac control line pulled off and capped, I think this just sets the pressure controller so that it bypassing the least amount of fuel, raising the press to max.

The brakes work great, no hissing sound, so I think they must be getting normal vacuum.

The main thing I need to know is if that vac press. in the intake manifold is normal.....or low, indicating I have a vac. leak somewhere.

Should I look at the EGR system? THey look like they could be the original parts with nearly 200K moiles on them. Could this cause a sudden loss of power, slowing down to a crawl after driving some miles? Will definitely check the PCV valve out!

At least my oil pump, water pump and timing belt change went well, and it is no longer leaking a drop of oil anywhere or leaking any coolant either.

THe other issue I have is with the fan control switch. I found the original bad, had a pinhole leak in the bulb, and so it had stopped switching...it was just stuck grounded, and this keeps the fan off. Well I went and bought a new one from Autozone. Install it and I have the same problem...the fan never turns on at normal temps. I had to again pull the connector off to get the fan to run. So I checked the new switch by immersing it in boiling water. Yes, at 212 deg. the switch does open, so it is functional. but isn't the fan switch supposed to turn fan on at around 185-190 deg? The car will sit there idling in hot summer weather, and it never turns the fan on! Thanks, Geronimo

thanks, Geronimo

Now it has a much worse problem. It is over- heating. When I was working on the throttle body, I bumped the temp sensor (the gauge sender), and knocked the contact part off. So I had to remove the part where the radiator hose, and sensor and vacuum switches are mounted. I installed a new sensor, and remounted the assembly on the engine with the two nuts. That is all I did. I thought that perhaps the calibration of the new sensor was not the same as old one, but I checked the engine temps with a laser temp gauge when it was edging up towards the red zone, and it was at 225 deg. ! Shut it off real quick! The sensor was not quite the same, the sensor body is a little longer than original, but don't see how this would cause some major restriction of water flow. The radiator is topped off and cooling system is not leaking a bit...not even at 225 deg.

Before working on throttle body and changing the temp sensor, it was running at mid-scale on temp gauge as it should. There is only one fan coming on, the one on the right side, but it is apparently adequate (when all is normal) enough by itself, it seems. Or should both come on ? From the Haynes manual, I think the RH side one is supposed to be turning on with the A/C....but it is the RH one that is being controlled by the fan control switch on the thermostat housing. The AC isn't working yet, not charged, so I would guess that is why one fan, in my case the LH one...is never coming on.

IF only I was rich and could just take it to an auto repair shop. ;-)

Geronimo

I think the vacuums there are a little low, even with the tiny ports. You should be getting near full manifold vacuum, which you stated is about 20in. So you are getting vaccum from the engine, and pretty health at that, 17-22 normally.

EGR is a simple system that really doesn't go bad except they get plugged up with carbon and stick either open or shut. Do a simpel test:

First measure the vacuum at the EGR port hose. You should get 0 (no vacuum) at idle. If you get vacuum at idle at the valve, you have a problem. Also pull vacuum of the EGR valve and see if the engine runs rough or stalls. If so, it's ok. If no change then the valve is not working.

Let's see: your upper rad hose gets hot and then the lower get warm to hot? If so your thermostat is opening and your water pump is working. Because if hot water isn't coming out into the radiator, your fan switch isn't going to turn the fan on (while at the same time your engine overheats because hot water stays there).

So your fan is working as you bypassed the switch. At least that's good. The two coolant fan switches operate at different termperatures. Usually 20 def-F apart. If one is at 185 then the other is at 205. The higher one switches on the condenser fan if it's not on already because of the AC.

You should probably first check coolant flow:

- Water pump (is the right pump installed? is the timing belt properly tensioned? etc

- Thermostat. (is it operning and the valve opening height within spec?)

The new coolant sensor: is it spec'ed for 1988 3SFE? If so, physical apperance may change over the years. What's important is the temperature response:

See Figure 1, Autozone's free repair guide:

BTW, the guide implied the 3SFE has only 1 level of fan switching, at

199 deg-F only. Then the AC fan is controlled by turning the AC on only. I am not sure about this.

ger> Now it has a much worse problem. It is over- heating. When I was

John, would the cooling fan switch for the second fan be on top of that header (or whatever is called) mounted on the left side of engine, the same header that the top radiator hose goes to, and has two temp-controlled vac switches and the gauge sensor ? There is on the top side of it another switch or sensor that has a two-conductor connector...its not like the fan switch on the thermostat housing that has a single conductor. I am asking because I need to locate and check the other fan switch, see if it is bad also.

The thermostat is a new one and is known to open fully, and as I said, after initial test runs after replacing timing belt, water pump, oil pump, was maintaining the engine temp gauge at mid-scale. It is only after checking throttle body and changing out gauge sensoro that it has the over heat problem.

Could the timing have jumped? Would this cause overheat possibly? Yet engine power has not changed a bit, nor idle speed.

Autozone apparenty gave me the fan temp switch that actuates at the higher temp! They can't tell you what the specs are for any electrical part, that is the problem with Wells/ Autozone parts. No specs are included in the box with the part! But I think the same is true of internet vendors....no specs. So I guess I am out $35 for an incorrect part that they don't accept returns on as it is now used.

I didn't really have to bypass anything to get the RH fan running...I just leave it unplugged from the new fan switch. Funny thing is that I pulled both fan control relays...yet the fan still contines to run! Have to pull the CDS fuse to get it to stop. I am having lots of trouble with this, partly because I am an ameteur, and also because the wiring diagram in the Haynes manaual is just a generic one covering several model years, and on my car is not the same as shown. The diagram doesn't show two fan temp switches, it shows the AC fan as only controlled by a relay.

Thanks, Jim

Also, please clarify which vacuum port should not have vacuum at idle. There are ports /hoses on the modulator and on the EGR valve itself.

I do know that there is no vacuum signal to the vac. control port on the top of the EGR valve, and nothing changes when I connect/disconnect it.

Thanks, Jim

Checked radiator hoses from a cold start. Yes, after a couple of minutes at idle, the upper hose got hot, before the lower hose began to heat up. So it seems water pump and thermostat are still OK.

And I looked at that coolant header again, and there is another electrical temp switch, a single conductor one, besides the two- conductor one I reembered seeing. Probably that's another fan switch. Will take it out and check it also. The Haynes manual shows the AC /auxiliary fan power going through a high-pressure switch.

Geronimo

Well, it dawned on me that yes, indeed, incorrect timing can make a car overheat, so I checked the timing marks. The cam timing has jumped WAY off! I did not get the new timing belt properly tensioned...or the ten miles or so I put on it has stretched it. I know you can't rely on the spring tension alone. I put more than the spring tension before tightening the tensioning idler bolt down...but obviously it still wasn't enough. What is the trick to ensure it doesn't jump again?

geronimo

Sometimes when trying to suss out a problem in an engine, we can go off on a tangent, losing sight of the original problem.

If your engine *IS* overheating, then that has to be investigated first, as it is a major problem which may cause other symptoms to distract you.

Make sure your laser temp-gauge is actually correct in saying the coolant is reaching 225F. As coolant has a higher boiling point than water a cooling system in good order will also raise the boiling point by use of system pressurisation, its imperitive to know the exact coolant temperature.

When I was

That's possible, but not to a great degree generally.

but I

It wouldn't do that.

The radiator is topped off and cooling

OK, so the system pressurisation is working.

Exactly where the gauge sits, varies from car to car. This is why you need an acurate separate test gauge to measure engine temp. I've found that just measuring the head temparature (the metal itself) is just as good. Especially aluminium heads like the Camry.

There is only one

AFAIK, the fan controlled by the sensor in the radiator bottom tank is the one which responds to excess heat. The AC fan has its own control when the AC is on.

Yep.

The common things to check have been done in that the water-pump is new and the coolant is not leaking out. This leaves the thermostat which maybe stuck shut and the head-gasket or head itself. If either of these is allowing coolant to be sucked into the combustion chambers, the engine will start to run rough and lack power due wetting of the spark-plugs. Also, over time, the coolant level will drop in the expansion resevoir. This will show when the engine has cooled again.

Usually when this occurs, but not every time, compression gases are forced into the water-jacket and appear as a constant stream of bubbles exiting the coolant when viewed at the radiator cap hole in the upper tank. The elbow on the upper tank where the cap sits needs to be topped-up with water so the bubbles can be seen. These days, mechanics have sensors which can pick-up any fuel or other exhaust gases at the radiator fill hole.

Inspecting the spark-plugs which are located in deep recesses in the cam-cover, will show as very clean if they have been subject to coolant leakage. If the headgasket or the head itself is responsible for your overheating, you'll be embarking on a repair job which for a novice maybe difficult. It's important to get the diagnosis right however, and a few bucks for a good mechanic will be worth it.

Jason

The last message didn't seem to get posted so I'll try to reconstruct it:

The CDS 30A fuse is for the condenser fan. The RDI 30A controls the radiator fan. The radiator fan is supposed to be on the driver side and the condenser fan on the passenger side.

There is a engine coolant temperatuer (ECT) *switch* on the inlet pipe (driver side) with the thermostat. This controls the radiator fan and should have a switching range of 181-199F. It should turnon at 199F (no continuity) and off at 181F (continuity). The radiator fan can also be controlled by fan relay #2 and #3 by the ECM in conjunction with the condenser fan.

The sedans have only one ECT switch; the all-trac AWDs have TWO ECT switches. The second one is on the water outlet pipe (driver side). The order looking from the radiator to the firewall is: thermo-vacuum switching valve right above radiator hose, #2 ECT switch for AWD models, engine temperature sensor (a variable resistor as described in the Autozone repair guide I sent, Figure 3 on how to test).

By pulling the ECT switch, your radiator fan should operate. If not, you may want to check the motor operation by jumpering it to power. Be careful here with live battery current.

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Yes, too advanced a timing can cause overheating. This can be verified by looking at the cam mark with crank mark at 0 deg. No timing light will do here.

Check the AutoZone guide on how to tension the belt. You should do it exactly to the word. You should probably change this belt out now it's gotten stressed by who know what force. I'd use a Gates timing belt from your local NAPA store. Have you changed out the pulleys as well?

Compare the guide here with Haynes:

Tighten all bolts to specified torque. Use a $12 torque wrench from Harbor Freight on sale will help. Sears Craftsman ones are excellent too which I enjoy using.

As specified: with the timing belt on the pulleys and all aligned, loosen the tensioner pulley bolt by 1/2 turn to allow it to operate. And turn the crank several complete turns (I do it more than the

2-turns specified, it's the only difference). It'll tend to jump tooth during this stage beacuse of valve spring tension so go slow and smooth here. Torque the pulley bolt to 31 lb/ft after making sure all the marks are still aligned. Then crank another several complete turns.

If the belt stretches after a proper installation, then you may have something seizing and causing the belt to stretch. BTW, over-tensioning can also do this.

ger> Well, it dawned on me that yes, indeed, incorrect timing can make

Correction: inlet pipe is on the passenger side.

Thanks John for the good info. Well then, someone has been doing some creative wiring on this car before I bought it. When I pull the ECT switch conn. on the thermostat, the *RH* side fans runs (having lost the ground from switch). The LH side fan has never run. Not having experience with Camrys, I assumed it was the aux fan for the compressor/condenser cooling, and since the AC has lost its charge and compressor is never running, that that was why that fan was never running. But it makes more sense for the AC fan to be on the RH side since it blows on the compressor directly. Does it make a big difference on cooling performance? I have been doing test runs of the engine with the RH fan running constantly (temp switch connector pulled off) any time ign power is on...and it was for a while maintaining temp at mid-scale--- that is until something happened with the timing. Is easy enough to swap fan power wires, or fans if the LH one is no good. Can buy a condenser fan later when I get the AC fixed.

Thanks again, Geronimo

On 13 Aug 2006 15:59:17 -0700, snipped-for-privacy@hotmail.com wrote:

Maybe Toyota made some production changes. When you pull the ECT switch, the driver side fan (radiator fan) is supposed to turn. The condenser fan (passenger side), according to schematics and repair guide, is supposed to turn at low speed below 194F regardless of AC switch being On or Off (!).

So after the important things are sorted out, check the radiator fan (driver side). You should jumper the power to the fan, because if the schematics is right then the pressure switch may have a play in the operation of the radiator fan.

ger> Thanks John for the good info. Well then, someone has been doing some

Roger on that! Thanks!