De Lorean EuroTec

I have an ear-splitting whistle coming from the engine, difficult to locate (the whistle, not the engine. I know where that is.). About 4.8kHz if you're interested. Momentarily dips in frequency when throttle depressed but returns at similar pitch. I suspect a vacuum leak. I can't see anything immediately visible so I think it's probably coming from under the inlet manifold, where I gather there is a device called the 'thermal control valve' on the vacuum schematic, and 'thermal vacuum switch' on the spares site. (I wish the terminology would be standardised - much less confusing for the uninitiated.) Also, I have a cold running problem, in that, after starting, fairly easily, the engine dies if I try to rev up. OK once it's warm in a few minutes. This suggests to me that the control pressure regulator is not operating. (I've checked the electrical contacts there, but I think this wouldn't give quite the same symptoms.)

My question is, how on earth do you get to the thermal control valve? It seems like the G-spot of the Delorean - I believe it exists but I don't know how to get to it. My hand is too big to delve into the little crack. Knowing my luck and clumsiness, I could do more damage trying to take things apart, which never go back together properly. I can't find a 'how to' on YouTube but I'm guessing that someone must have done this at some point and know the tricks. It could be just a loose connection or something broken. I see replacements are available.

All helpful advice gratefully received. Otherwise car going well and lamenting no CarFest this year.
Tony in Southampton

Hello Tony

You can isolate the thermo-vac switch by disconnecting the vacuum pipe from the inlet manifold that goes to the thermo vac switch, then use a short vac pipe with a screw in it to block the hole at the inlet manifold. If the noise goes away then you can look into this area.

The thermo vac switch is on the V shaped coolant pipe, and needs the inlet manifold removed to get to it. This is assuming that the issue is with the thermo vac switch itself.

You could consider giving your air path a smoke test, where smoke is entered into the system then you see if there's any smoke coming out or leaking.

I have heard high pitch whistle of failed gaskets on the W pipe on the inlet manifold.

Aha! Thank you for that tip. I will try tomorrow. I found another useful Youtube video (so many have the carburated engine - I didn't know that was an option) showing the manifold stripdown and the switch. I did finally manage to get my hand into the valley of death via the 'top right' entrance and by thrusting to the limit of my skinny arm just touch the G spot, sorry, Vacuum switch. Nothing seemed broken and all three pipes were attached and I could feel two of them for their entire length with no obvious holes or crumbling deterioration. The third was the manifold connection and the lack of triple-jointedness of my fingers precluded my following it all the way. But with your help, I think I'm on the right track. I don't have a conventional W pipe as I have the single turbo fitted but I shall look at the relevant joints as well. Cheers

They'll be the same gaskets. Yours might be prone to failure as they would be subject to boss pressure, probably.

Have you had any boost problems lately that coincide with the start of the squeal?

I disconnected the vacuum tube at the manifold and plugged it as you suggested and it made no difference. So I guess my diagnosis of the vacuum switch is incorrect. Randomly I found a very loose spark plug, but tightening that made no difference either, except that cold acceleration was a bit less hesitant, so my worry about the control pressure regulator may be unfounded, or a separate issue. I gave the W pipe substitute parts a jolly good wiggle and there was no chage in the whistle. The air sensor housing has some play in it, but, again, moving this causes no change. It's so difficult to auditorily locate a single frequency sine wave but it doesn't appear to be 'near the surface'. I'm a bit worried that it might be a bearing squealing but since it's not engine rev dependent, except dipping briefly on revving up it seems unlikely. I shall persevere.

I had a weird loud shrieking whistling sound on the way to eurotec one of the years.

One of the injector clips had come loose. The injector seat had popped out from its housing . Took a short while to spot as it was not immediately obvious.

Just re clipped the injector spring clip and pushed the injector back down fully and it was sorted.
The sound was loud, never heard anything like it before.
Might be worth a look to see if they are tight and snug as they should be?

Shane

Hi Tony

Have the vac hoses been replaced or any of the gaskets recently ?
And or injectors or injector seals?


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Have you tried removing the air con belt in case it is one of the idler pulleys? (And subsequently the alternator belt for the water pump & alternator? )

Does the audible frequency change in relation to engine revs/ load?

Thanks so much for all the hints. I haven't ever investigated injectors but I'll have a little rummage, though the ones on the left are pretty tricky to get at. It really is a piercing whistle. I've not noticed any turbo problems, and the engine hasn't had anything done to it for some time so no new gaskets or injectors. But the loose spark plug made me worry, so I'll check injectors.

The way the turbo is set up, all the gubbins seems to hang on the inlets where the W tube normally is, so it must be quite a strain. But, as I said, I can heave it all about and the whistle doesn't change so I don't think there a leak caused but the mechanical strain of the turbo stuff.

The whistle frequency drops momentarily when I rev up but then quickly returns to as it was before so doesn't seem engine speed dependent as I would expect a bearing on a pulley to be, but worth a shot I guess. I know it's ot belt squeak as I've had that before and I know what that sounds like.

I can record the sound but I don't know if I can attach it to this posting.

There's always something........

(My rear courtesy light has stopped going out now after the delay - I suppose I'll have to look into the mess that is the relay compartment - all rewired with random coloured wires!)

Hi
Try changing the courtesy light position back and forth first it may just be bad contact.

If the engine hasn’t had anything done to it for sometime , it sounds like it needs a full overhaul/service?
Vac hoses,
Plugs
Cap/Arm
Leads
Injectors and seals and clips
Gaskets etc

Al


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