Inlet valves or is it?

[Shotaro]

Quick one, on start up car tries to die, drops revs and have to press the accelerator to get it to 1000rpm where it just about stays before dropping to 800 idle, so got me thinking probably inlet valves, but have a few other symptoms...

If I put the rear demister on it drops the revs to about 400-600 rpm
Exhaust puffs on start up for about 2-3 minutes
Tappetts sound quite rattly
Engine/car shakes for 2-3 minutes on start up

All this is at start up, after 2-3 minutes and driving after that seems ok, but does shake and puff sometimes when stopped

Anyone know this sounds like inlet valves or anything else?

Cheers

[dunc]

Yeah could well still be inlet valves, do a compression test cold (dry and then wet if required) to confirm.

Dunc.

[Shotaro]

Brilliant, cheers mate, is there any risk of damaging anything if I drive it with buggered inlet valves?

[dunc]

I had knackered inlet valves (on a low mileage engine!) and put up with it for a month or two but it became a bugger to start so that convinced me to get the job started, didn't cause my engine any harm but wouldn't like to say that running it like that is harmless as advice to someone else if you know what I mean?

First step is doing a compression test before anything else though, you never know it might be another cold start problem.

Cheers,

Dunc.

[davetherave]

mine did exactly the same, do the cold comp test as stated above, will reveal all. I got away with just lapping new valves in. As you've got the head off, why not give it a quick rebuild.

[Shotaro]

Cheers Dunc for the honesty and not just saying "yeah you'll be fine", I'll get a compression test done

davetherave, I'd love to do a rebuild, but I have zero mechanical skills so would have to pass it over to a garage unfortunately

[sxbaz]

i ran mine for a year with worn inlets, it was only on 40k. I didnt do mega milage but it was used daily, eventually the following winter came in and it was impossible to get started, it flooded all the time, shook so badly the engine was rocking its tits off.

Do some compression tests and see what it shows up, then you might wish to consider picking up a spare head and getting all the work done on the new head with valves and new stem seals etc, then have them swapped over with a new HG, that way you can still use the car while the new head is being put together.

[Jonny Wilkinson]

Another indicator is to check the vacuum reading at idle (assuming you have a boost gauge).

If it reads -18 inHg that's normal.

If it reads lower, its an indicator of worn inlets. This is because, if the valves are not sealing properly, the compression stroke blows the compression mixture back into the plenum reducing the vacuum that would normally exist in the plenum on the compression stroke at idle.

There were a faulty batch of inlet valves fitted to some 93/94 CA18DETs that wore out very quickly. I had to do mine after 31K miles. Worn inlets on earlier CAs with > 75K miles is not that unusual either.

If a compression test does show it to be inlets, take it to someone like DAL (in Gravesend) that has built so many CAs he can do top-end rebuilds with his eyes shut.

[davetherave]

Cheers Dunc for the honesty and not just saying "yeah you'll be fine", I'll get a compression test done

davetherave, I'd love to do a rebuild, but I have zero mechanical skills so would have to pass it over to a garage unfortunately

Watch you tube mate, easy learning.

[2Bobrocket.]

Yip had the problem with a Ca18det 93 inlet valves i cant remember of the top of my head what the valves numbers had stamped on them if it was 84 or not please correct me if I'm wrong but the valves on the head where so much worn the where flush with the head new valves and seals and lapped all the valves light skim and new gasket it was giving 170 psi over each bore couldn't ask fore anything better tbh for a stock car

While your at it id stick on a MHG 1.6mm or a 1.9mm after skim as when you want to up the boost later this has been done, dropping to a 8.5 comp ratio with the 1.6 and a 8.1/8.0 comp ratio with a 1.9mm tis been a while since but if the heads off its worth doing it right first time, an old saying measure twice cut once still applies here

Im only back a sort time so correct me if im wrong troops

Archie

[skyshack]

Poor valves won't stop it holding idle under electrical load.

Check the TPS idle switch. Mode IV ECU check will indicate switch operation when throttle is shut and open. If it doesn't work, check throttle is properly shut (someone may have set it a bit open to set idle) then re-check and adjust TPS.

Check the ACC valve. With warm engine unplug it, revs should drop from 850rpm to 800rpm. Plug it back in, revs should surge and settle back to 850rpm. If it stalls or runs slower than 800rpm when ACC is unplugged adjust the base idle to 800rpm - hex bolt on rear of idle air assembly. If rpm doesn't drop set base idle down to 800rpm. If it doesn't surge strip and clean the idle air assy.

Give it a dose of Wynn's Hydraulic Valve Lifter Treatment or 1/2L of ATF for 20 gentle miles before oil change. Check it doesn't rattle when warm on lift off at 2K-2.5K rpm - that's big ends.

New plugs? NGK Iridium.

When you have done all that and get here the shaking could be poor compression. Head gasket or valves. Need a cylinder leakage test to find which.