5 GT Turbo Rebuilt engine - No vacuum. Help!!

[JGM]

Hello everyone,

First thank you Mark Davis for inviting me to come here.

I have a 87 Red GT Turbo. After some 6 years gathering parts, it underwent a almost total rebuilt some 3 years ago.
Andybond, happy to oblige with the photos barrage...

Disassembly :


After paint:


Engine assembly:




Took almost one of everything still available at the Renault dealer at the time

Engine bits:
- OEM Mahle Liners, Pistons and rings
- Mahle standard size crank shells
- Mahle standard size rod shells
- Washer on oil pump to increase pressure
- Corteco/Meillor Blue head gasket
- 12.9 steel head screws
- CatCams 270 in standard pulley.
- Piper "uprated" valve springs
- New valve stem seals
- Valve guides were deemed OK by the machine shop.
- K-Tec GroupA carb and 2 standard carbs.
- K-tec T25 turbo (230 was its name i think)
- Volvo 480 Sachs Clutch
- Renault 11 turbo gear box
- Mocal oil cooler with thermostat
- Copper Core radiator
- Double alloy intercooler
- Walbro fuel pump
- Malpassi fuel pressure regulator
- 2.5 " SS Scorpion exhaust with custom chambered muffler.

- New subframe
- Full Koni shocks
- Full new seat sub frames, cloth and foams
- All new doors, windshield, window rubbers and seals

This helped a lot, thanks Renault!!






Finally at a local car gathering



But it has problems and i need some help diagnosing, please!!!!

Since the very first run the engine demanded the GrpA carb mixture screw to be wound out around 8 to 10/5 turns from fully in.
The idle was steady(ish) but was very very weak, just turning head lights or the radiator fan cutting in would bring idle at the tach +-800rpm to 450/500 rpm.

I finally got hold of a set of two good standard carburetors but the car would only run, very rough, with the choke flap closed or if the mixture screw was around 12/13 turns from totally in. Cold start (ambient 23ºC), engine doesn't run bellow 1500rpm, rpms controlled inside the car with the choke mechanism.


Summary of 2 months testing done:

- Checked for vacuum leaks on manifold, carb, oil breather pipes, brake booster and master cylinder. Some found, corrected and double checked.

- Tested carbs, Re209 module, on two other R5 GTT and all was good, idle, no detonations on boost, AND misture screws at around 3/4 turns from fully wound in.
- Tested Re209 power supply, crank position sensor resistance and coil spark strength according to Renault manuals available online. All in spec.

- Tested with oem renault plugs, NGK BR8s and BR9s, all the same, gaped correctly.

- Pressure tested intake manifold with the one way valves still screwed in at 5bar+, then immersed in water and no leaks or cracks found.
- Intake manifold sent to machine shop to check and correct contact surfaces.

- Vacuum tested the brake booster and its hose. Held constant -0.9 bar vacuum for 2+ hours.
- Oil breather system has both restrictors in place, hoses and plastic T were pressure tested to 1.5 bar (21 PSI) with no leaks

- Malpassi adjustable fuel pressure regulator set to 4 psi(i think) at idle. Plenty of gas, "Believe Me!" like Trump says.
- Catcams assures cam should work fine without adjustable vernier pulley.

- Cold compression test with 142.5 psi all round, good i think?
- Tested valve lash/gaps from the std 0.15/0.2 to 0.25/0.25 to MAX catcams recommends 0.3/0.35 . No change.

My spark plugs are usually like this but afr are always way too lean.




Engine vacuum readings are difficult to pinpoint, needle fluctuates violently at idle between -5 to -9.5 PSI (converted from my -0.35 to -0.65 bar). Increasing rpms the needle settles at around 7.9psi.(0.55 bar). Reading taken with and without brake booster and oil breather systems attached to manifold. same problem.

In this site How to Use and Interpret a Vacuum Gauge you can see various scenarios and mine appears to similar to scenario 8, BUT the machine shop deemed the valve guides OK.

Need help checking if the timing is correct, I have searched for a Haynes manual but no luck.
Aligning the flywheel at the bell housing the dizzy points to either piston 1 or 4 every 360 degrees crank rotation, but how to be sure the cam is right?

Very very sorry for lengthy post.

 

[Mark Davis]

@Markey Mark BD @Brigsy @Fordy

 

[Brigsy]

Do you have the breather restrictor fitted in the short breather rubber pipe from the inlet manifold ?? That can cause crappy idle if not fitted.

If it is fitted then personally i would be double checking if the cam is actually what it is supposed to be as from reading the brochure for cat cams they dont do a 270deg duration? I have no experinece with cat cams as only fitted piper.

When i ran a cam that was roughly 276 duration (similar to piper 300) the engine idled rough and required lots of fuel to idle 13/14afr. I had to drill the idle jet out as the mixture screw was right out on the stock idle jet. I also had very little vacuum - i recall the needle used to bounce all over the place. The big question is does the engine make decent power ? Drill the idle jet out to .47 and set it at 1000 rpm 13afr if needs be.

 

[JGM]

Hi Brigsby,

What you describe is very similar to what i experience. Power wise i never measured it having all these issues, but it surely wants to keep going past 7000rpm (tach) with the Grpa carb in. If this cam proves to be that rough i will just fit the standard one and be done with it! Goal was road usability with a little something more...

I have both restrictors in place, the 1.7mm in the small breather pipe and the 7mm one in the pipe going to turbo telephone hose. Readings are roughly the same with all disconnected from the manifold. The engine almost stops by just screwing in the lobster top on it, when running standard carb.

I ordered a Piper 270 at K-Tec but got this one instead, sent without even consulting/warning me at the time, David Kirk apologized later saying there was a stock shortage from Piper. It was fitted standard timing and some fancier piper valve springs.

Contacted k-tec and Catcams to check this cam and was assured it would work with the standard sprocket, starting to realize "work" may have several meanings....

 

[Brigsy]

262 duration should be pretty smooth to be fair and fine for street use. Maybe check the timing, vernier pulley is generally essential for timing up an aftermarket cam. Not sure on how good the catcams grinds are could be far out ? Could be different to the spec sheet ? I think it may require some investigation.

 

[JGM]

262 duration should be pretty smooth to be fair and fine for street use. Maybe check the timing, vernier pulley is generally essential for timing up an aftermarket cam. Not sure on how good the catcams grinds are could be far out ? Could be different to the spec sheet ? I think it may require some investigation.

My thoughts exactly, 262 should be usable. OK, when i describe the idle as rough I mean it as a series of intermittent misfires, not that heavy cam constant lumpy idle.

Timing is something that scares me a bit to be honest, thus i went to the only local mechanic to have it done, but as I have done all else myself I think I may have a go at it. As a starting point, and assuming standard sprocket timing was set, this rough running should indicate a retarded cam, correct? (exhaust valve closing too late on final cycle).

Will inquire CatCams once more about any type of serial number engravings on the cam I could look for!
Do you have any idea if the chap in this thread 5 GT Turbo - What Camshaft should I use in my EFI C1J?... ended up using catcams ?

 

[Brigsy]

Stick a timing wheel on and dti to see where its at before stripping the engine down. They do pop on idle occasionally so could be correct? I thought you meant really choppy idle like the engine was on 3 cylinders.

I think the timing would need to be way out to cause problems. + - 4deg usually idles ok.

Generally a cam can require more fuel on idle though. If it drives ok and timed to spec i would be tempted to jet it to suit. Maybe bin the grp a carb and jet up a good stock carb. Grp a is poor at best.

 

[JGM]

Stick a timing wheel on and dti to see where its at before stripping the engine down. They do pop on idle occasionally so could be correct? I thought you meant really choppy idle like the engine was on 3 cylinders.

I think the timing would need to be way out to cause problems. + - 4deg usually idles ok.

Generally a cam can require more fuel on idle though. If it drives ok and timed to spec i would be tempted to jet it to suit. Maybe bin the grp a carb and jet up a good stock carb. Grp a is poor at best.

Correct, almost like running on 3 cylinders and lots of exhaust popping (not loud bangs)..starts to smooth out when almost removing the mixture screw but never settles.

I have nowhere here where I can gett a timing wheel, is it ok to print one and use it? I will dedicate some days to reading about timing, but sorry have to sound like a noob, what is dti ? (diesel turbo injection Renault )

The grpA carb was a last resort as I had similar engine issues back in 2006/2007 before the restoration, where the engine hesitated badly on steady speeds only running good on full throttle, idle was always good if i recall. at the time everyone pointed at the carb, so I went with the "fashion" at the time, GrpA. and it ran better, but not good, so the car was parked for some 7 years until the restoration 3 years ago...and guess what, still with similar issue....

 

[DaveL485]

Brigsy would it run like this if the dizzy drive was 180° out?

JGM check your cam timing, its the only answer thats not really been investigated. I assume the flywheel sensor is completely OE and not messed with? Do you have a timing strobe?

 

[JGM]

Brigsy would it run like this if the dizzy drive was 180° out?

JGM check your cam timing, its the only answer thats not really been investigated. I assume the flywheel sensor is completely OE and not messed with? Do you have a timing strobe?

Hi Dave

Yes, the crank position sensor is OE and new from Renault, the wires are not inverted (tried inverting them but there was no improvement) and its resistance is within spec (measure few days ago 238Ohms or Kiloohms i think).
No, I dont have a timing strobe, but can ask around tomorrow for one.

I have been turning the engine by hand and in every 360º flywheel rotation the alignment markings on the flywheel and the dizzy points to either the engine (4) or the radiator (1).
Yesterday I removed the timing chain cover, when Mark Davis posted his video and we started chatting I ended up writing this post and didn't continue to check the timing marks. As soon as the family starts dispersing (catholic Easter celebrations) I will get under it and check those markings also...

 

[JGM]

At this point all I am left is the cam uncertainty and the vacuum gauge fluctuation indicating worn valve guides.
I am suspicious about the valve guides also, because I always have a noisy valve "train" no mater the gap I go with. Cold the engine is quieter but when in temperature it sounds almost like a 89/90 Ford Fiesta 1.0C that you can clearly hear and recognize in the distance....
The head is the same as before when i had a running hesitation and the guides were deemed ok by the machine shop. In all cases I will replace all, guides and valves in the nearby future.

 

[JGM]

Stick a timing wheel on and dti to see where its at before stripping the engine down. They do pop on idle occasionally so could be correct? I thought you meant really choppy idle like the engine was on 3 cylinders.

I think the timing would need to be way out to cause problems. + - 4deg usually idles ok.

Generally a cam can require more fuel on idle though. If it drives ok and timed to spec i would be tempted to jet it to suit. Maybe bin the grp a carb and jet up a good stock carb. Grp a is poor at best.

Got it, dti! I have several at work.
I will fashion a timing wheel and get busy and post the findings.

 

[Brigsy]

Brigsy would it run like this if the dizzy drive was 180° out?

JGM check your cam timing, its the only answer thats not really been investigated. I assume the flywheel sensor is completely OE and not messed with? Do you have a timing strobe?

You can run these engines with the dizzy 180deg out providing the leads are reversed to suit. Timing sensor placement does not really bother the idle either you can have it fully advanced or retarded and they generally run ok..to make a massive difference you need to be chopping the gearbox bellhousing and moving the sensor a lot further.

Tappit/valve train noise could be worn rockers causing incorrect clearances. What are the clearances set at ?? They do sound a bit like thenold fiesta kent engine with a hot cam in though, pretty normal.

I still think the cam might be a bit hotter than 262. If the timing is around 112 then next step would be to whip the cam out and check it.

 

[JGM]

You can run these engines with the dizzy 180deg out providing the leads are reversed to suit. Timing sensor placement does not really bother the idle either you can have it fully advanced or retarded and they generally run ok..to make a massive difference you need to be chopping the gearbox bellhousing and moving the sensor a lot further.

Tappit/valve train noise could be worn rockers causing incorrect clearances. What are the clearances set at ?? They do sound a bit like thenold fiesta kent engine with a hot cam in though, pretty normal.

I still think the cam might be a bit hotter than 262. If the timing is around 112 then next step would be to whip the cam out and check it.

For two years it had been at .20/.20, set it according to some older posts of yours and markeymark, but this last year always set to factory 0.15/0.20 . When setting clearances my father always made us turn the engine twice and re-check cylinder by cylinder on all our cars, and yes more often some correction is needed.

Its quieter when cold but noisy at temperature. My brother and friends started calling it something like the "Hot Sewing Machine", noisy and always sweating...

Will check timing wheel tomorrow, asked Jan from CatCams for some help on how to better identify the cam (serial number, etc).
I have measured the difference between a totally closed valve and a totally open one, from one spring top hat to another and it seemed to check out, sure it may not be an accurate method though.

 

[JGM]

While waiting on my dti to become available, I thought I should share the answer I got from CatCams.

Hello Jan,

I am having some difficulty to make this engine run smooth and after two months of continuous testing I have come to realize it comes down to either cam or valve guides. My engine is always unsettled and produces very very low vacuum!

How can I be sure the cam I have is the same as in the spec sheet you sent me with it (any engravings on it!)?
******************************************
Hello,

If you check the valve lift at tdc you should measure a valve lift of 1.1mm (with a valve clearance of 0.30mm) on both intake and exhaust valve. The Piper 270 only has 0.66mm/0.61mm which means the Piper cam will produce more vacuum at idle.

Best regards,
Jan

Well, the engine did work better in the first running in times with the gap set at 0.30 per spec sheet, now with 0.15/0.2 runs like sh*t...makes sense, less and less vacuum...

@Brigsgy , regarding your remark on trying to fuel it to suit, I had tried it in the past with a idle jet of .50 (went from .45 to .50), which allowed to regain adjustability with the idle mixture screw, but it rendered it sluggish everywhere else, which led me to believe i would be forced to readjust every single other jet in the carb...

One other thing, has anyone ever had a crack in the head intake/exhaust runners connecting one and another, if so what would the symptoms be?
My engine never had that pronounced exhaust burble I hear on others. Also I used to have loud as shotguns exhaust pops and bangs way before this rebuild and until the first running issues (2006/2007), that led me to the GrpA carb (by K-Tec), after those and the GrpA fitting never again did I got those sweet exhaust pops and bangs at overruns, almost no burble either, only annoying drone sound... Always the same OE manifold, OE turbo elbow and straight through exhausts.
Is it remotely possible or am I missing something else!?

Thks guys for your help and sanity checks on my sleep deprived conspiracy theories...This car its been a handful...

 

[Brigsy]

Idle jet only fuels low rpm or off throttle (under 1200 rpm from memory) so should not make any difference across the rest of the rpm. Do you have an afr gauge fitted ? The grp a bored out carbs are usually very rich in the mid range. I would be refitting a stock rejetted carb, you will see better drivability/economy & fuelling when jetted correctly.

Bangs on overrun are usually due to lean idle mixture/lean fuelling off throttle. As for cracked head do you mean a minor crack between the valve guides ? Mine has been cracked for many years now, does not really cause any issues.

 

[Brigsy]

Also i think .15/.20 clearances are too tight for a hot cam. If you have gone a little bit too tight that could be causing rough idle. I have had rough idle with stock cam when the clearances are too tight - also causes rough running low down. Clearances of .20/.25 or .25/.30 would be better - slightly more tappy but tappy engine usually = happy engine

 

[JGM]

Back in 2006/2007 I tried a 135 main 0.9 ac carb and with it the engine hesitations and misfires disappeared, but the overruns bangs returned, and also gave me a slightly higher boost pressure, which led me to send the carb to k-tec to have it rebuild as a grpA carb, thinking my old OE one wasn't fueling enough for some reason.

I have a AEM 30-4900 afr fitted with this rebuid, and is always showing lean except on full throttle. Looked for exhaust leaks, none found.

I mean the runners, the passage ways from the manifolds gasket until the valve seats. Its just odd mine does no burble and those conflicting afr readings...

 

[JGM]

Also i think .15/.20 clearances are too tight for a hot cam. If you have gone a little bit too tight that could be causing rough idle. I have had rough idle with stock cam when the clearances are too tight - also causes rough running low down. Clearances of .20/.25 or .25/.30 would be better - slightly more tappy but tappy engine usually = happy engine

I went it the stock gaps in ignorance of thinking i had a milder cam, drove for a year with 0.3, then tried 0.2 and this last weeks 0.15/0.2 (these are the stock cam gaps by Renault)...and course always worse...the tappet sound at 0.3 bouncing of the side of the road bugs my OCD, I just cant ignore it.
The dti arriving and if all is correct I will just pull the cam out and stick OEM back in it. 95% of driving it is below or about 2500rpm and its just unpredictable/annoying to drive it.

Won't the 0.25/0.3 clearances also accelerate rocker/valves/valve seats wear as well, due to the increased acceleration?

 

[Brigsy]

I think the larger clearances will stop wear to the cam lobes from memory thats the reason behind it. Stock clearances are .20/.25 - the smaller clearances are for n/a c series. I think you would be unlucky to have a crack through a port in the head.