175 CD2SE not rich enough

V12-Engine
1

Greetings:

Just got the S-III back up and running after a 4-year hiatus :frowning:

Charged the battery (I took it out while sitting) and with nothing else done it started up after 20-30 revs - running poorly as would be expected, gas pouring out of the jet covers on 2 of the 4. Pulled all the carbs and then float bowls to get whatever crud was in there out. I had bought new jet covers from Joe Curto before it went to the dark side of the shop- so the o-rings are new, I applied a liberal bead of vaseline to the o-rings and then inside the plug after installing them. Checked that the floats were all 0.65" from the deck- GTG there.

Also took all the jets out from the jet-carriers to inspect - all B1-BH needles as the service manual calls for. Set them all to 1/2 turn from full rich. Re-installed the carbs, drained the tank of the old gas, added 5gal fresh 91octane. Started car, balanced the airflow, figured some would be running rich due to setting so close to full rich. Could not get the rich indication when slide lifted 1/4". Lifting of each carb seemed to cause a stumble. So added another 1/4 turn towards rich and at this point I only have another 1/4 turn to go. Still no indication by the slide-lift test of rich adjustment. So I took it out for a local drive. I have to say it runs great! In the past, when I would come to a stop the car would try to die, now it doesnā€™t. Conclusion is that I had the carbs set too lean previously. Also heating has always been a problem if the temp gauge is reading correctly. The car will run at the ā€˜Nā€™ of the word ā€˜Normalā€™ for maybe 2-3 miles but then rises to the ā€˜lā€™. The fan comes on at ā€˜lā€™, and a thermal imager tells me that the temp at the thermostat housing is at about 165 or so when fan comes on. So maybe thereā€™s no problem.

So I drive the car maybe 10 miles (highway) to get gas, and otherwise run the car some to get the juices flowing, running great! Nice to be back in the saddle. Get it home, roll up the drive and into the shop and shut it down overnight. Back out this morning and pull the plugs to inspect. Driverā€™s rear 3 are all bone-white. The rest are pretty well tan, with passenger front 3 having black soot around the inside of the steel jacket but all have tan ceramic and tips.

Last time the car was running - 4 years ago, I couldnā€™t get the driverā€™s rear carb to richen up enough - and todayā€™s situation is no different assuming the final quarter-turn to full-rich wonā€™t be enough. What else can I try? If I canā€™t get it rich enough to tan the plugs from their current white, is it safe to drive the car?

Other issues I have to deal with are a 70# compression on the A4 cylinder, and a faint rattle from the front of the motor at times.

I rebuilt the motor in 1988 and I have 10k miles on the clock from then, 34k total original miles on the car. I did not replace/update the timing chain tensioner at rebuild - dumb me.

Anyone comment on the richening failure, Iā€™d sure appreciate it.

2

An air leak some where ? A missing vacuum hose ? A cracked vacuum hose ? Float height ? Stuck needle valve ?

3

None of the above - checked them all when I tore down the carbs. Vacuum hose new and connected.

4

Ok, I think the issue was the bypass valve was opening - I took the offending carb off - removed the bypass valve, separated the valve body halves, and screwed out the nut adjusting the spring tension on the valve. Also cleaned the brass plate and landing spot on the valve body and lubed with vaseline to seal.

Took the car out for a spin last night - about 5 miles of highway. Temp was initially running at the ā€˜Lā€™ of ā€˜Normalā€™ because of idling while adjusting the offending carb. As I was driving it at about 60 or so, it dropped some, and by the time I was pulling off the highway back home had dropped to ā€˜rā€™. Heated back up as I was rolling up the drive, fans were on by the time I pulled it into the shop bay. Thermal imager said 195 at passenger thermostat, about the same at driverā€™s.

The car pulled pretty well in 2nd although started hesitating at about 4500 or so (still to lean?). Recall all the carbs are now set to within a quarter-turn of full rich on the needles.

Anyhow- shut down overnight to cool, pulled the driverā€™s rear plug this morning and the bone-white is now to brownish-white. so some progress.

BTW, I donā€™t have the bypass valves hooked up, I see no need for them - I enjoy the burble of the pipes as the car decelerates!

At this point, maybe I should accept the warm nature of the car and make sure it doesnā€™t go past the ā€˜Lā€™ at any time.

I guess now Iā€™ll go out and continue the detailing work - getting ready to show it at a local venue next weekā€¦

5

The car pulled pretty well in 2nd although started hesitating at about
4500 or so (still to lean?).

That actually might be an ignition issue. Are you still running the Opus
ignition? I know that with the later CEI ignition with dual coils, if you
disconnect the secondary coil itā€™ll run fine up to about 4500 and then peter
out. Youā€™d think itā€™d start misfiring or something, but owners have reported
that it just lacks ooomph to go any faster. Owners have also reported that
replacing the POS Opus with something better makes the car run a LOT
better even though they thought the Opus had been working fine!

BTW, I donā€™t have the bypass valves hooked up, I see no need for them

  • I enjoy the burble of the pipes as the car decelerates!

Yeah, I like that too. Bad for the environment, but the sound is great!

ā€“ Kirbert

6

Kirbert,

I replaced the original OPUS with a distributor from a later model - has the iron wheel with 12 fingers to trigger the sensor, clear plastic cover on top, vent pipe at top and side of cap. I believe it is the retard actuator which hooks up to the driverā€™s rear carb underneath for vacuum.

BTW, since this is Kerbert Iā€™m communicating with here, yes, I did rebuild the unit when I got it, and yes it was seized! Yes, just three days ago I took the cap off and made sure I had counterclockwise free movement, added three drops of :frowning: regular motor oil to the top of the spindle.

Also can you comment on my description of the way it runs heat-wise? Seems to me that if it is cooling down while cruising, then itā€™s probably OK. I believe the temp needle has always lurked near the ā€˜Lā€™ of ā€˜Normalā€™. Iā€™m just paranoid of overheat I guess, since it seems about the only time I drive it is in warm weather.

Thanks!
TameCAT

7

The distributor with the iron star wheel is the Lucas CEI. Wise choice IMHO, but it requires either two bottle-style coils or a single low-impedance coil to rev over about 4000.

Any car that gets hot while moving slowly but cools down on the expressway either has too little airflow from its radiator fans or too little coolant flow at low engine speeds. Iā€™ve also heard something about running too lean (?) can cause overheating problems like this, but IMHO if a mixture issue pushes the cooling system beyond its limits it was on the verge of catastrophe anyway.

This is a SIII E-Type weā€™re talking about, is it not? Original vertical-flow radiator? Two pathetic little electric fans? Never fiddled with such a car myself, but Iā€™ve always doubted those fans were up to the job. If you want the engine to stay cool in traffic, you might need to upgrade. Also make very sure thereā€™s no crud in the radiator fins obstructing the airflow.

If you want to conduct a test, you could let the car idle in the driveway while spraying down the radiator fins with a garden hose. If that results in nice cool running, your problem is lack of sufficient airflow.

You also have different thermostat housings than us XJ-S guys. I donā€™t recall the configuration, but I presume you have some sort of bypass arrangement directly back to pump inlet that gets closed off when the thermostats are fully open? Do you have the correct thermostats in there?

8

Ok, well the radiator is not the original - I did have it re-cored about 15 years ago with a high-capacity core, so it isnā€™t the issue (I donā€™t think), but this car has sat in the shop for most of the last 15 years. :frowning: So perhaps there could be some plugged passages. Yes, it has the crappy two little fans, but they kick on at about 170 or so at the thermostat housing which seems to correspond to the ā€˜Lā€™ of the word ā€˜Normalā€™ and they cycle on for maybe 4-5 seconds then off for about 10-20 sec. Car wonā€™t heat up past L sitting at idle because the fans do come on. Ambient here is about 70 these days. If I take off with it from this state of heat, it will stay between the M and the L as long as Iā€™m on the secondary rural road (45mph). When I hit the highway, the temp starts dropping ā€“ and will go as low as the ā€˜Oā€™ or ā€˜Rā€™ at about 65mph. If I stop for any length of time, itā€™s back to ā€˜Lā€™ and the fans come on.

Iā€™m pretty finicky about the radiator fins - so only the occasional bug should be blocking it.

As to thermostats, they are 165-degree variety, and sit at the front of the engine on top. Like I said, Iā€™m probably paranoid about this but do not want the car to start dropping valve seats. I may have that already as there is a ticking coming from the A-bank somewhere, and A3 has only 75# of compression compared to the 105 of the other cylinders.

I guess in thinking about it, if the only time the fans come on is when the car is at rest, then Iā€™m probably okay. But the other night, I pulled in from a run where the highway speed had the temp down to the R - pulled it into the shop and raised the bonnet to check temp at the thermostat housings, 190 on one and 197 on the otherā€¦ Fans were on - temp gauge still said L-

I will try the garden hose test here at some point soonā€¦

Thanks!

TameCAT
Mike B

9

Somebody mentioned the fans. There okā€¦will do the job. But also there was a mention of crud in the radiatorā€¦thats the real headache. Replace or send out to get cleaned. I think you will find car runs much cooler. Lets keep kitty topped up too ! 50/50 any product coolant will do.

10

Yes, I had the radiator re-cored about 20 years back ā€“ havenā€™t driven it that much since ā€“ maybe 3k miles or so.

Does anyone have any experience with a ā€˜waterlessā€™ coolant that apparently carries more heat per volume of coolant than regular-

11

Maybe a flush using Prestone rust remover. 3K in 20 years creates lots of internal rust . Waterless coolant great stuff in the right application, mainly sealed systems, not for Jagā€™s with lots of hoses, occasional leak, an unsealed.

12

You didnā€™t fully answer the thermostat question. Itā€™s not merely temp spec but also bypass construction. A lot of people fit tstats from their local parts store without a spring-loaded moving ā€˜footā€™. These act like poppet valves to close off the bypass port once the stat opens. You could measure the distance travelled in a saucepan test versus the distance the port face is below the fitment flange. If you leave the bypass open, or use a tstat with insufficient foot travel, you hurt the cooling capacity by never having all the coolant flowing through the radiator. The fans are plenty good enough, althoigh the cage could do with a vertical rib between them, to preserve core throughput if one fan ever dies.

13

Being ā€œtoo richā€ or ā€œtoo leanā€ is a relative term:- rather than simply adding fuel, consider removing air.

The throttle linkage will allow you to alter the amount of air on a per carburettor basis; the needle height in the jet is a per carburettor variable setting dependent on vacuum and the various vacuum hoses or bypass valves or temperature compensators may cause a slightly different amount of air to reach different carburettors.

kind regards
Marek

14

Peter,

I have in the past replaced the 190 thermostats with 165 variety. While they did come from the local parts store, they do have the spring and are not the poppet type. They are normally shut as I recall, and this prevents water in the engine jacket from being circulated till the temp of the tstat is reached. Then they open allowing circulation to the radiator.

Been driving the car more, and can say that while outside temp is now more or less 70F, the only time the fans come on is if the car is sitting in traffic after having been driven for a bit. It does not like stop-and-go, although when I say that I mean the temp gauge goes above the ā€˜mā€™ in ā€˜Normalā€™ if I get into stoplights. Other than that, it seems to stay in that range as long as air is flowing through the radiator.

I think the issue with the rear driverā€™s carb being too lean was the air bypass valve not being adjusted to keep pressure on the valve. Iā€™ve got that fixed now-

Still wondering if the carbs are too rich - the car runs well, but Iā€™ve used a half-tank in about 60 miles-

TameCAT
Mike B

15

Marek,

AFAIK, Iā€™ve solved the issue of the too-lean carb via the mal-adjusted air bypass valve. What I havenā€™t done yet is to compare the plugs from the offending quadrant to the others to see if color is close. They are no longer bone-white though so I think Iā€™ve got it fixed. Re: removing air, I know I have the carbs balanced relatively well in terms of air flow so I donā€™t want to mess with the throttle linkage-

The other niggling worry is the ticking on the A-bank and the low compression on A4 at 75# vs the 105 for the others on that bank. I need to redo this test.

TameCAT
Mike B

16

We may be talking at cross purposes, but you do need the poppet type. It sounds like functionally the car is there or thereabouts but two wrongs donā€™t make a right.

17

I have in the past replaced the 190 thermostats with 165 variety.

Not a smart move.

While they did come from the local parts store, they do have the
spring and are not the poppet type.

Not sure what that means. Our thermostats are poppet type, they just
have an additional seat that closes off the bypass when hot.

They are normally shut as I
recall, and this prevents water in the engine jacket from being
circulated till the temp of the tstat is reached.

Everything is wrong about that statement. Nothing in the thermostat design
in the Jaguar V12 is capable of preventing water in the engine jacket from
circulating.

Still wondering if the carbs are too rich - the car runs well, but
Iā€™ve used a half-tank in about 60 miles-

Are you still running those 165 stats? Try installing reasonable temp stats,
get the car off choke, maybe itā€™ll get better fuel economy.

ā€“ Kirbert

18

Kirbert,

re: Everything about that statement is wrong,

Guess I donā€™t understand then - these thermostats sit on a housing at the front top of the water rail at the top of the motor - the forward and only outlet of these housings run straight to the radiator- so logic says that if the thermostats are shut (maybe there are small bleed holes in the thermostat plate, I canā€™t recall) when the engine is cold, there will be no coolant circulating back to the radiator, at least from the top of the motor where the warmest coolant will be.

And - the car is not on choke. The manual choke lever fully seats home, the choke light goes out, manually checking the choke arm on the carbs show they are fully shut, and there is the required gap at the high-speed idle arm at the carb.

TameCAT
Mike B

19

Guess I donā€™t understand then - these thermostats sit on a housing at
the front top of the water rail at the top of the motor - the forward
and only outlet of these housings run straight to the radiator

There are three connections to the thermostat housing: One from the outlets
on the head, one to the radiator, and one back to the pump inlet. Nothing
obstructs the connection from the head. As the thermostat heats up it closes
off the outlet to the pump inlet while opening the outlet to the radiator.
Regardless which way the coolant leaves the thermostat housing, there will
be flow through the cooling jacket ā€“ unless, of course, the radiator is totally
obstructed.

And - the car is not on choke.

Youā€™re telling us you canā€™t seem to get it rich enough. Youā€™re just trying to
run it on choke without the choke on, as though somehow that makes it all
better. Get the engine warmed up before deciding what the mixture needs to
be.

ā€“ Kirbert

20

Ok, Kirbert -
Give me a little credit here.

And please re-read the post I made after getting the bypass valve straightened out. Viz, the offending carb appears at this point to be rich enough now once I got the bypass valve adjusted so the disc presses firmly against the body. This judgement by pulling a plug after running the car on the highway and noting that it was no longer bone-white but similar in color to those from other carbs. I have zero idea where you conclude that Iā€™m running it with a virtual choke-

No, I have not gone in with the colortune yet for a fine-tuning of the jet adjustments. Yes, I do need to pull the plugs again and check color. If as I suspect, they are not sooty black, Iā€™m going to conclude Iā€™m pretty close on the mixture.

Yes, the car runs pretty well - well enough for me at this time. Iā€™ve had it to 5-grand on the tach in second gear and it was still pulling hard.

Yes, maybe there is crud in the radiator after sitting, I need to probably remove it and see whatā€™s inside. But as long as itā€™s going to hold to or below the ā€˜mā€™ or ā€˜oā€™ in the word ā€˜Normalā€™ while out on the highway Iā€™m going to consider it running cool enough to drive it.

FWIW, with the previous 175 or 185 degree thermostats, it would sneak up into the area above the ā€˜lā€™ on a regular basis as I recall.

Bottom line, Iā€™m pretty happy with it now except for the harbinger ticking I hear at the A-bank and the low compression on A4. But thatā€™s another issue.

TameCAT
Mike B