Life-Savers for owners of a Volvo P1800ES and others with D-Jetronic

I wrote this article for Svenska P1800 Klubben some time back – it may help those of you who own such a beautiful old car and want to enjoy the ride. 

I am pretty sure I am not the only one: It is not acceptable for me to give up and throw the awesome D-Jetronic out, just because it is a nasty bitch sometimes. It is what came with the car – and when it works fine, it is really very good. So why switch to a carburetor? Well, there are some reasons but let me tell you: they can be overcome.

When I got my first ES, now I have an E as well, an idiot had it before and I could find all kind of colorful items across the whole thing. It was no surprise that the Engine did not enjoy to be started. Hoses were off, the pressure box way broken AND from an Opel. The injectors were bad and two were from some other cars (but hey, they looked the same!). The Auxiliary Air Vent was long gone, so was the thermal timer for the cold start valve. Did I mention the Throttle Valve Switch? Simply put: It was a mess.

Now when you inherit such a mess, it is easy to give up and switch to mechanics. But I am not the type to give up and – as said earlier – I want to preserve the original state. When its intact and properly adjusted, the D-Jetronic is just lovely.

So I started digging. And I found some ways forward which I would like to share with you all, as they may short-cut some of your efforts.

What needs to be intact for a D-Jetronic are all the parts mentioned before: AAV, TVS, Pressure Sensure, Thermal Timer. Also the throttle valve needs to be intact – so the bearing of the throttle valve needs to be ok. Also all hoses need to be intact, correctly attached and secured. False air intake will make the whole system go limbo, so this requires attention.

So if all this is great, the injectors are the correct ones, fuel pressure right – you should be able to enjoy your E / ES with D-Jetronic.

Unfortunately, as many of you know, having the parts intact is not as easy as it may sound. But there are ways to obtain parts or have the broken ones repaired, which make life so much easier.

The easiest actually was to find a source for the Throttle Valve Switch – a part, which on eBay can be super costly and with no warrenty that the part will work.

If you have the older version, Bosch 0 280 120 012, you can buy a repair kit at this website. The assembly is pretty straight forward.

On eBay, you can even get the board for the newer version Bosch 0 280 120 039, which would be favorable since it is more durable and better weather-proofed than the old one. The seller comes from the Netherlands and I have repaired all my switches with his kit, with perfect results. He also offers to repair the Switch for you if you don´t think your hand is calm enough: https://www.ebay.de/usr/peuver

The best bet for the pressure sensor is to check the vacuum (there needs to be a vacuum and the sensor needs to hold it) – if you cannot do it, I am sure a local repair shop with some experience will be able. Generally speaking, a pressure sensor that does not hold the vacuum will be trouble in many ways and needs to be replaced. Fortunately, Bosch is now offering the refurbishing of such sensors, but it does not come cheap. I would say though it is worth it because then your sensor will be fine for the next 45 years.

It is important that you have the right sensor, since the ones for B20E and B20F engines have different values and you need to use the correct one for good results – you find it here.

A bigger problem is the Auxiliary Air Valve. The way it is built is that it contains a wax like substance that expands with heat – and pushes a moving part over the auxiliary air intake, cutting it off. This is obviously very simply put. The wax element tends to leak and lose its ability to expand and cut off the air – the part is broken. Unfortunately, BOSCH does not refurbish them and new ones are almost impossible to come by – and even if you find a part, bear in mind that the wax element is probably as worn out and bad as the old one. Since prices are obscene on eBay, you will much rather contact “Dr. D-Jet”, Herrmann Ebner in Austria. Mr. Ebner obtained some of the original machines from Bosch to fix the AAVs and when you get your part back from him, it is better than new: ebner.oldtimer@gmx.at

Last not least comes the Thermal Timer, which newer versions of the E / ES have installed on the lower rear of the engine block, passenger side. The BOSCH number is 0 280 130 200 but that number will do you no good: there are no new ones to get, BOSCH stopped making them a long time ago. You could alternatively use a timer of the K-Jetronic (Volvo 164), but that is no perfect fit and also old and long time since. The timers are made of bi-metal switches in Balelite and screwed right into the engine block – the heat usually makes the switches break inside and create a short circuit, which may not even be visible from the outside.

I have worked with Bosch on fixing the issue and have just mastered the last challenge. While you will not find an official replacement (yet), I can tell you what works:

BOSCH has a new Thermal Timer in stock, which is an electronic one – BOSCH F 026 T03 101. This one will work – but not fit your engine on either end. The connector for the cable harness does not fit, but that is an easy fix with standard crimp plugs. A bigger problem is that the switch sensor is a bit longer and also the thread does not fit. This I could fix with the help of a local turning shop. Also the old switch is connected to the engine block with an adapter – just bring the old switch and the new one to your turning shop of trust and they will be able to custom make an adapter for you. In my case, I had it made at Rainer Koch Maschinenbau in Hanau near Frankfurt in Germany (where I live): +49-6181-14462 / Möhnestraße 20, D-63452 Hanau. You may call Mr. Koch and reference my adapter (Nils Winkler in Bad Vilbel), he should have the measures still.

I have tried all of the above solutions and they work really well – especially solving the problem of the Thermal Timer has cured a major head-ache for me and makes for a smooth cold start of the engine.

If time is of essence – the season is still ongoing and the perfect weather makes us drive our dear old Ladies more – you can also check out Buttkereit. They have a lot of re-manufactured parts in stock. Most come from the same sources but you don’t have to wait – obviously, that comes at a price. 😉